We demonstrate a heterogeneously integrated III-V-on-silicon-nitride mode-locked laser with 710 MHz repetition rate. A versatile two-step micro-transfer printing approach is employed to enable low-loss integration on a commercial foundry low-index photonic platform.

Poelman et al. (2023), CLEO 2023 conference contribution

Here, we design and experimentally demonstrate a proof-of-principle integrated silicon nitride device capable of imprinting the Talbot phase relation onto in-phase optical combs and generating the two-fold self-images at the output. We show that the GHz-repetition-rate bright and dark pulse trains can be doubled without affecting their spectra as a key feature of the temporal Talbot effect. The designed chip can be electrically tuned to switch between pass-through and repetition-rate-multiplication outputs and is compatible with other related frequencies.

Wu et al. (2023), Communications Physics

A discrete, tunable photonic integrated laser is showcased for multiwavelength spectroscopy of CO2, H2S, and H2O. The laser combines an AlGaInAsSb/GaSb type-I quantum well-reflective semiconductor optical amplifier with a Si3N4 photonic integrated circuit (PIC). Operating at room temperature, the laser emits at 2670.42, 2629.12, and 2594.27 nm, with mW-level average powers.

Ojanen et al. (2023), Laser & Photonics Review

We have designed and fabricated a hybrid integrated laser source with full C-band wavelength tunability and high-power output. The external cavity laser is composed of a gain chip and a dual micro-ring narrowband filter integrated on the silicon nitride photonic chip to achieve a wavelength tuning range of 55 nm and a SMSR higher than 50 dB. Through the integration of the semiconductor optical amplifier in the miniaturized package, the laser exhibits an output power of 220 mW and linewidth narrower than 8 kHz over the full C-band.

Chen et al. (2023), Optics Express

We demonstrate CMOS-compatible, integrated, high energy Q-switched lasers in the eye-safe window (1.9 µm), with an on-chip output pulse energy of 80 nanojoules at a repetition rate of <1 MHz with single fundamental mode operation in a compact footprint.

Singh et al. (2023), CLEO 2023 conference contribution

In this work, we demonstrate large mode area (LMA) waveguide based CMOS compatible watt-class power amplifier with an on-chip output power reaching ~ 1W within a footprint of ~4mm2. The power achieved is comparable and even surpasses many fiberbased amplifiers. The thickness of the thulium doped aluminum oxide gain medium (Tm3+:Al2O3) is 1.35 µm on top of a silica cladding layer within which a 800 nm thick SiN layer is buried (such a thick SiN allows seamless integration to conventional nonlinear photonics components).

Singh et al. (2023)

We propose a hybrid integrated self-injection locked (SIL) narrow linewidth laser with adjustable feedback intensity, through an adjustable Sagnac loop reflector (ASLR) coupled to a high- Q micro-ring resonator. The intrinsic linewidth is reduced to 60 Hz, and the locking range without phase compensation is extended to 6.3 GHz. This work has important application value in the field of coherent detection and precision metrology.

Su et al. (2023), IEEE Xplore

We designed and fabricated two on-chip tunable lasers for CV-QKD (continuous-variable-quantum key distribution), and demonstrated a high-performance system based on these sources. Because of the high output power, fine tunability, and narrow linewidth, the involved on-chip lasers guarantee the accurate shot-noise-limited detection of quantum signals, center wavelength alignment of nonhomologous lasers, and suppression of untrusted excess noise.

Li et al. (2023), Photonics Research

We demonstrate a high-performance integrated laser exhibiting broad wavelength tuneability near a 2.6 µm wavelength region. The laser is based on a Si3N4 photonic integrated circuit incorporating a tunable reflector and a AlGaInAsSb/GaSb quantum-well gain element. A tuning range of 170 nm (2474–2644 nm) and single-mode CW operation with a maximum power of 6.4 mW at room temperature are demonstrated.

Ojanen et al. (2023), Lasers & Photonics Reviews

In this work, we demonstrate complementary metal-oxide-semiconductor (CMOS) compatible, rare-earth gain based large mode area (LMA) passively Q-switched laser in a compact footprint. We demonstrate high on-chip output pulse energy of >150 nJ in single transverse fundamental mode in the eye-safe window (1.9 µm), with a slope efficiency ~ 40% in a footprint of ~9 mm2. The high energy pulse generation demonstrated in this work is comparable or in many cases exceeds Q-switched fiber lasers. This bodes well for field applications in medicine and space.

Singh et al. (2023)

The microchip OPO device, based on the third-order (χ(3)) nonlinearity in a silicon nitride microresonator, produces output signal and idler fields widely separated from each other in frequency ( > 150 THz), and exhibits a pump-to-idler conversion efficiency up to 29 % with a corresponding output idler power of > 18 mW on-chip. This methodology can be readily applied to existing silicon photonics platforms with heterogeneously-integrated pump lasers, enabling flexible coherent light generation across a broad range of wavelengths with high output power and efficiency.

Perez et al. (2023), Nature communications

A self-injection locked laser with narrow linewidth down to 345 Hz is presented here, which is composed of distributed feedback (DFB) semiconductor laser and high quality (Q) factor silicon nitride (SiN) external cavity, with tunable sagnac loop reflector on the basis of add-drop type high Q microring resonator (MRR).

Su et al. (2022), SPIE digital library

We exploit the low-loss features of Si3N4 waveguides and demonstrate a hybrid laser comprising a GaSb gain chip with an integrated tunable Si3N4 Vernier mirror. At room temperature, the laser exhibited a maximum output power of 15 mW and a tuning range of 80 nm (1937 – 2017 nm).

Zia et al. (2022), Optics Letters

Guo et al. (2022), IEEE Xplore

Liu et al. (2022), IEEE Xplore

A hybrid InP/SiN tunable laser based on microring resonators exhibiting 40mW fibercoupled output power and 5kHz linewidth is demonstrated.

Calò et al. (2022)

We generate a quantum light source of eight pairs of correlated photons in a wavelength range of 25.6 nm within telecom wavelength using a SiN micro-ring with an FSR of 200 GHz.

Fan et al. (2022)

This paper demonstrates a widely tunable III-V/Si3N4 hybrid-integrated external cavity laser with maximum output power 34 mW, 2.5 kHz intrinsic linewidth, a relatively faster switching time ~ 60 μs, and side mode suppression ratio more than 70 dB over the tuning range of 58.5 nm. The external feedback circuit is based on 800-nm-thick Si3N4 waveguides with an optical confinement factor of 87%.

Guo et al., IEEE Xplore (2021)

We demonstrate an adaptable method for ultrastable control of low-energy femtosecond pulses based on common electro-optic modulation of a continuous-wave laser light source – the electro-optic modulation of a continuous-wave laser light source can also generate optical frequency combs.

Carlson et al., Science (2018)

In this work, we propose and experimentally demonstrate such an On-chip optical delay lines (ODLs) based on chirped waveguide Bragg gratings (CWBG). This device is fabricated on a low-loss 800-nm-height silicon nitride platform, combining 20.11-cm long index-chirped multi-mode spiral waveguide antisymmetric Bragg gratings with a directional coupler. The bandwidth of this circulator-free ODL is 23 nm. The total GD is 2864 ps and the delay-bandwidth product is 65.87 ns·nm, which both are the largest values achieved by on-chip CWBG reported to our knowledge.

Li et al. (2023), Optics Express

This study proposes and demonstrates a dispersive silicon–nitride OPA that allows for passive wavelength-tuned steering of a line beam with an elongated vertical beamwidth.

Bhandari et al. (2022), Scientific Reports

A 56 nm wavelength tuning range, 2.9 kHz linewidth, maximum output power 22.5 mW, and static frequency step bandwidth 56 GHz hybrid integrated external cavity laser is reported based on silicon nitride vernier microring resonators functioning as an optical bandpass filter. A frequency-modulated continuous-wave (FMCW) signal is generated under synchronous modulation with a chirp bandwidth of 7.68 GHz at a 1 kHz repetition rate.

Liu et al. (2022), IEEE Xplore

We fabricated in silicon nitride technology a proof of concept steerer with beam waist 0.36° ×0.175°, addressing a field of view of 15° ×2.8°. A new design iteration is also reported with and 0.24° ×0.16° beam waist and 15° ×11.2° field of view.

Munoz et al. (2022), IEEE Xplore

We propose and demonstrate an optical phased-array-based bidirectional grating antenna (BDGA) in silicon nitride waveguides. The manufactured BDGA could achieve an enhanced beam-steering efficiency of 0.148 deg/nm as well as a stable spectral emission response in the wavelength range of 1530–1600 nm.

Lee et al., Photonics Research (2022)

We present a hybrid integrated SiN-polymer OPA for realizing an efficient LiDAR. The polymeric modulators are integrated with a SiN power splitter and grating antenna.

Im et al., IEEE Xplore (2021)

Jha et al. (2021)

We propose and demonstrate a backward-emitting silicon nitride optical phased arrays (OPA) incorporating a reinforced grating vector, which provides efficient wavelength-tuned beam steering along the longitudinal direction.

Im et al., IEEE Xplore (2020)

The demand for higher data rates in next-generation mobile wireless communication
systems (6G) has led to significant interest in terahertz (THz) waves as a highfrequency, broad modulation bandwidth carrier wave. In this study, we propose and demonstrate a wireless data transfer in the 560-GHz band using low-phase-noise THz waves generated by photomixing of a pair of distributed feedback lasers injectionlocking to Kerr micro-resonator soliton comb.

Tokizane et al. (2023), Arxiv

We present the dispersion engineering of a three-microring photonic molecule via thermo-optic effects. Despite the overall normal GVD, local regimes of normal and anomalous dispersion are tailored by fine-tuning the microcavities’ supermode frequencies.

Trinchão et al. (2023), CLEO 2023 conference contribution

Optically generated terahertz (THz) oscillators have garnered considerable attention in recent years due to their potential for wide tunability and low phase noise. Here, for the first time, a dissipative Kerr microresonator soliton comb (DKS), which is inherently in a low noise state, is utilized to produce a stepped-frequency THz signal (≈ 280 GHz).

Nawwar et al. (2023), Arxiv

We present the concept and design of a 100 GHz PIC-based nonlinear frequency division multiplexed transmission system in which four b-modulated spectrally overlapping channels are spectrally stitched without frequency guard bands to obtain a continuous spectrum.

Moscoso-Mártir et al. (2023), Science Direct

We demonstrate degenerate optical parametric oscillation in a triple-state silicon nitride photonic molecule. DOPO is generated with a phase-coherent dual-tone pump scheme, and the phase-matching conditions are optimized by tuning the resonances with microheaters.

Tomazio et al. (2023), CLEO 2023 conference contribution

We demonstrate a miniaturized optical frequency division system that can pgenerate microwaves with superior spectral purity on a CMOS-compatible integrated photonic platform. Phase stability is provided by a large-modevolume, planar-waveguide-based optical reference coil cavity and is divided down from optical to mmWave frequency by using soliton microcombs generated in a waveguide-coupled microresonator. Record-low phase noise is achieved, and its heterogeneous integration with lasers, amplifiers and photodiodes holds vast application potential.

Sun et al. (2023)

We introduce nonlinear networks—systems of nonlinear photonic elements that observe a programmable set of conservation rules, and highlight their diverse capabilities by demonstrating an optical frequency synthesizer, which operates at nearly arbitrary output frequency exceeding the state of the art in synthesized conversion bandwidth. Using a codesigned microresonator network, our synthesizer is based on four-wave mixing (FWM) spectral translation of a tunable laser and a frequency comb from a silicon nitride chip.

Black et al. (2023), Physical Review

Here, we report broadly tunable milliwatt-level second-harmonic generation in a small free spectral range silicon nitride microresonator, where the pump and its second-harmonic are both always on the fundamental mode. By carefully engineering the light coupling region between the bus and microresonator, we simultaneously achieve critical coupling of the pump as well as efficient extraction of second-harmonic light from the cavity. Thermal tuning of second-harmonic generation is demonstrated with an integrated heater in a frequency grid of 47 GHz over a 10 nm band.

Nitiss et al. (2023), Optics Express

We demonstrate that the all-optical inscription of second-order nonlinearity through the coherent photogalvanic effect allows not only degenerate but also non-degenerate sum-frequency generation in silicon nitride waveguides. Several multiphoton absorption processes can occur simultaneously, such that their quantum interference allows for the inscription of distinct charge gratings for quasi-phase matching of several second-order nonlinear processes within the same waveguide.

Yakar et al. (2023), SPIE digital library

For the first time, we report integrated firstorder quasi-phase-matched backward second-harmonic generation (BSHG) enabled by seeded all-optical poling. We carried out the demonstration in an integrated Si3N4 waveguide buried in SiO2 fabricated by LIGENTEC SA using its AN800 platform.

Yakar et al. (2023)

The non-degenerate sum-frequency generation quasi-phase-matching gratings are reported on a silicon nitride chip, and supports the theory of coherent photogalvanic effect with time dynamics analysis

Yakar et al. (2022), Laser & Photonics Reviews

A quantum light source of eight pairs of correlated photons in a wavelength range of 25.6 nm within telecom wavelength using a SiN micro-ring with an FSR of 200 GHz.

Fan et al. (2022)

Based on the third-order (χ(3)) nonlinearity in a silicon nitride microresonator, an OPO device produces output signal and idler fields widely separated from each other in frequency (>150 THz), and exhibits a pump-to-idler conversion efficiency up to 29 % with a corresponding output idler power of >18 mW on-chip.

Perez et al. (2022)

CW-driven dissipative Kerr solitons in a high-Q standing-wave (intrinsic Q ~ 4 million) Fabry-Perot microresonator on a silicon nitride chip with an FSR ~ 19 GHz.

Wildi et al. (2022)

This paper thoroughly presents the design strategy to reliably attain an ultra-wide soliton microcomb with dual-modes separated by ∼10 GHz in the silicon nitride (Si3N4) platform.

Weng et al. (2022), APL Photonics

Huang et al. (2022)

Through sign-alternating the dispersion in a CMOS compatible silicon nitride waveguide, we present a scheme to get up to 1000 nm bandwidth Supercontinuum Generation, achieve an efficiency enhancement factor of 2800, and lower the pulse energy requirement from nanojoules to 6 picojoules.

Zia et al. (2022)

We implement thermally assisted electric-field poling, which allows charge carrier separation in the waveguide core and results in an effective second-order susceptibility (χ(2)) inside the Si3N4 waveguide, making linear electro-optic modulation accessible on the platform for the first time.

Zabelich et al. (2022), ACS Photonics

We examine theoretically and experimentally the nonlinear coupling mechanism in a 1 THz repetition rate silicon nitride resonator and demonstrate four-wave mixing Bragg scattering between the different wavepackets forming the multi-color soliton, with the microcomb ranging over 150 THz, yielding a complex all-optical and integrated synthetic frequency lattice.

Moille et al. (2022)

We present optically reconfigurable quasi-phase-matching in large-radius silicon nitride microresonators, resulting in up to 12.5-mW on-chip second-harmonic generated power and a conversion efficiency of 47.6% W−1.

Nitiss et al., Nature Photonics (2022)

We demonstrate a photonic molecule composed of two coupled microring resonators on an integrated nanophotonic silicon nitride chip, designed to generate strongly squeezed light uncontaminated by noise from unwanted parasitic nonlinear processes.

Zhang et al., Nature Communications (2021)

We experimentally demonstrate the optical frequency division of an optically carried 3.6 THz reference down to 300 GHz through a dissipative Kerr soliton.

Tetsumoto et al., Nature Photonics (2021)

We report the generation of broadband single-mode (degenerate) quadrature squeezed vacuum from an integrated nanophotonic device based on two coupled silicon nitride microring resonators.

Zhang et al., scienceOPEN (2020)

We demonstrate a highly tunable second-harmonic generation in a silicon nitride integrated photonic platform.

Nitiss et al., Optics Letters (2020)

We report demonstrations of both quadrature squeezed vacuum and photon number difference squeezing generated via strongly driven spontaneous four-wave mixing below threshold in silicon nitride microring resonators.

Vaidya et al. (2019)

We experimentally demonstrate stimulated four-wave mixing in two linearly uncoupled integrated Si3N4 micro-resonators.

Tan et al. (2019)

We describe research on an optical-frequency synthesizer in a low-power chip-scale package that provides a laser output with a programmable optical frequency across 50 nm of bandwidth centered at 1550 nm, with a resolution smaller than one part in 10^14. Optical synthesizer is composed of a heterogeneously integrated III-V/Si tunable laser, which is guided by dual dissipative-Kerrsoliton frequency combs fabricated on separate silicon chips and pumped by off-chip laser.

Bowers et al. (2019)

We use a heterogeneously integrated III–V/silicon tunable laser, which is guided by nonlinear frequency combs fabricated on separate silicon nitride chips and pumped by off-chip lasers. With this tunable-laser and frequency-comb system, we demonstrate synthesis across a 4-THz segment of the C-band with 1 Hz resolution. Any application of an optical-frequency source could benefit from the high-precision optical synthesis presented here.

Spencer et al., Nature (2018)

Here we show that quasi-phase-matching via periodic modulations of the waveguide structure on a silicon nitride photonic chip provides a useful mechanism to control the evolution of ultrafast pulses during supercontinuum generation.

Hickstein et al., Physical Review Letters (2017)

Here, we demonstrate, for the first time, a broadband polarization-entangled quantum frequency comb by combining an integrated silicon nitride microresonator with a Sagnac interferometer. With a free spectral range of about 99 GHz and a narrow linewidth of about 190 MHz, our source provides 22 polarization entangled photons pairs with frequency covering the whole telecom C-band. The entanglement fidelities for all 22 pairs are above 81%, including 17 pairs with fidelities higher than 90%. Our demonstration paves the way for employing the polarization-entangled quantum frequency comb in quantum network using CMOS technology as well as standard dense wavelength division multiplexing technology.

Wen et al. (2023), Arxiv

The microresonator is optimized by tapered design with two waveguides of different widths. Through balancing the dispersion and loss, the bandwidth of microcombs is improved by 61.2% compared with the traditional one.

Tao et al. (2023), IEEE

We demonstrate a stabilization scheme for dissipative Kerr solitons in SiN-resonators achieving high comb stability and long-term operation. Measuring 10Hz level absolute Kerr comb line stability (at 1 second) close to the pump, resulting in kHz level stability in the spectral domain of NIR astronomical spectrographs.

Kordts et al. (2023), CLEO 2023 conference contribution

We demonstrate the first observation of optical frequency combs at the edge state of the Su-Schrieffer-Heeger model. We show soliton-induced edge-bulk interaction and edge-state hopping.

Tusnin et al. (2023), CLEO 2023 conference contribution

Dissipative Kerr solitons (DKSs) intrinsically exhibit two degrees of freedom through their group and phase rotation velocity. Periodic extraction of the DKS into a waveguide produces a pulse train and yields the resulting optical frequency comb’s repetition rate and carrier-envelope offset, respectively. Here, we demonstrate that it is possible to create a system with a single repetition rate but two different phase velocities by employing dual driving forces. In particular, we show that a multiple-pumped DKS on the silicon nitride chip may generate a two-dimensional frequency comb, where cascaded nonlinear mixing occurs in the phase velocity dimension as well as the conventional mode number dimension, and where the repetition rate in each dimension differs by orders of magnitude.

Moille et al. (2023)

Here, we provide a simple, robust, and universal solution to produce pulses with sufficient peak power to initiate nonlinear supercontinuum generation spanning hundreds of terahertz (THz) using off-the-shelf polarization-maintaining (PM) amplification and nonlinear fiber components. We show how to readily achieve pulses shorter than 60 fs at a repetition rate of 20 GHz and with peak powers in excess of 2 kW. The same technique can be applied to picosecond pulses at 10 GHz to demonstrate temporal compression by a factor of 9× yielding 50 fs pulses with peak power of 5.5 kW. These compressed pulses enable flat supercontinuum generation spanning more than 600 nm after propagation through multi-segment dispersion-tailored anomalous-dispersion highly nonlinear fiber (HNLF) or tantala waveguides. The same 10 GHz source can readily achieve an octave-spanning spectrum for self-referencing in dispersion-engineered silicon nitride waveguides.

Sekhar et al. (2023)

We demonstrate microresonators with programmable synthetic reflection which enables robust access to self-injection-locked microcombs operating exclusively in the single-soliton regime and with low threshold power.

Ulanov et al. (2023)

We demonstrate wireless communication in a 560-GHz band by using a photonic THz emitter based on photomixing of a 560-GHz-spacing soliton microcomb (using the SiN PIC of LIGENTEC) in a uni-travelling carrier photodiode together with a THz receiver of Schottky barrier diode. The on-off keying data transfer with 2-Gbit/s achieves a Q-factor of 3.4, thus, satisfying the limit of forward error correction.

Tokizane et al. (2023)

A THz (≈560 GHz) wave with a low phase noise is provided by a frequency-stabilized, dissipative Kerr microresonator soliton comb based on the SiN chips fabricated at LIGENTEC. The repetition frequency of the comb is stabilized to a long fiber in a two-wavelength delayed self-heterodyne interferometer, significantly reducing the phase noise of the THz wave. A measurement technique to characterize the phase noise of the THz wave beyond the limit of a frequency-multiplied microwave is also demonstrated, showing the superior phase noise of the THz wave to any other photonic THz oscillators (>300 GHz).

Kuse et al. (2022), Communications Physics

We experimentally demonstrate that multiple microcombs can coexist in monochromatically pumped Si3N4 microresonators.

Wu et al., Optics Letters (2022)

A soliton microcomb prototype with a microring of 75 GHz FSR on silicon nitride chip coupled to fiber array.

Xi et al. (2022)

In this paper, we investigate the switchability of dissipative cnoidal waves (DCWs) based on dual-coupled Si3N4 microresonators.

Wu et al., Optics Express (2021)

A dissipative Kerr-microresonator soliton comb is scanned by 70 GHz in 500µs, 50 GHz in 125µs, and 25 GHz in 50µs (= 500 THz/s). Furthermore, we propose and demonstrate a method to measure the frequency shift of all comb modes, in which an imbalanced Mach–Zehnder interferometer with two outputs with different wavelengths is used.

Kuse et al., Optics Letters (2021)

We propose an integrated photonics interposer to replace discrete components of microcomb based systems (microcombs, other nonlinear elements, lasers and photodetectors, etc) around 1550 nm by collecting, routing and interfacing octave-wide microcomb-based optical signals between photonic chiplets and heterogeneously integrated devices using silicon nitride photonics.

Rao et al., Light Science & Applications (2021)

By employing Pound–Drever–Hall locking and a microheater on the silicon nitride microresonator, we show continuous scanning of the soliton comb modes across nearly the full free-spectral range of the microresonator without losing soliton operation, while spectral features with a bandwidth as small as 5 MHz are resolved.

Kuse et al., Optics Letters (2020)

We report a comprehensive study of low-power, octave-bandwidth, single-soliton microresonator frequency combs in both the 1550 nm and 1064 nm bands, and get direct soliton generation with less than 40 mW of chip-coupled laser power utilizing fully integrated silicon nitride Kerr microresonators.

Briles et al. (2020)

A microphotonic astrocomb is demonstrated via temporal dissipative Kerr solitons in photonic-chip-based silicon nitride microresonators, directly providing a spurious-free spectrum of resolvable calibration lines.

Obrzud et al., Nature Photonics (2019)

A broadband visible (VIS) blue-to-red, 10 GHz repetition rate frequency comb is generated by combined spectral broadening and triple-sum-frequency generation in an on-chip silicon nitride waveguide.

Obrzud et al., Optics Letters (2019)

Manurkar et al., OSA Continuum (2018)

We demonstrate robust frequency-control strategies for near-infrared, octave-bandwidth soliton frequency combs created with nanofabricated silicon nitride ring resonators. The comb links wavelengths between 767 and 1556 nm from a 1064 nm pump laser, and the mode frequencies of the comb are spaced by 1 THz.

Yu et al., Physical Review Applied (2018)

We explore the creation of an octave-spanning, 15-GHz repetition-rate microcomb suitable for both f−2f self-referencing and optical-frequency comparisons across the near infrared. Efficient silicon-nitride waveguides provide a supercontinuum spanning 700 to 2100 nm, enabling both offset-frequency stabilization and optical-frequency measurements with >100 nW per mode.

Lamb et al., Physical Review Applied (2017)

Using a continuous wave–pumped, dispersion-engineered, integrated silicon nitride microresonator, we generated continuously circulating temporal dissipative Kerr solitons.

Brasch et al., Science (2016)

Here a multi-wavelength quantum light source using a silicon nitride micro-ring with a free spectral range of 200 GHz is demonstrated. The generation of eight-wavelength-paired photon pairs is ensured in a wavelength range of 25.6 nm. These results, at room temperature and telecom wavelength, in a CMOS-compatible platform, represent an important step toward integrated quantum photonic devices, which pave the way for realizing a large-scale quantum network.

Fan et al., (2023), Laser & Photonics Review

Here, we demonstrate the storage and recall of the entangled state of two telecom photons generated from an integrated photonic chip based on silicon nitride. Combining the natural narrow linewidth of the entangled photons and long storage time of 167Er3+ ions, we achieve storage time of 400 ns, more than one order of magnitude longer than in previous works.

Jiang et al., (2022)

We demonstrate controlled-NOT (CNOT) operation of a silicon nitride photonic integrated circuit using path-entangled photon pairs from a silicon-photonic integrated circuit as logical inputs, and the CNOT gate is by combining several silicon-nitride Mach–Zehnder interferometers for a linear-optical quantum gate. The fully packaged photonic circuits with electrical wire bonding and optical fiber bonding measures the logical-basis fidelity of CNOT operation better than 81%.

Lee et al., Optics Communications (2022)

A quantum light source of eight pairs of correlated photons in a wavelength range of 25.6 nm within telecom wavelength using a SiN micro-ring with an FSR of 200 GHz.

Fan et al. (2022)

Here we introduce a full-stack hardware−software system for executing many-photon quantum circuit operations using integrated nanophotonics on a silicon nitride chip: a programmable chip, operating at room temperature and interfaced with a fully automated control system.

Arrazola et al., Nature (2021)

We report demonstrations of both quadrature squeezed vacuum and photon number difference squeezing generated via strongly driven spontaneous four-wave mixing below threshold in silicon nitride microring resonators.

Vaidya et al., arXiv (2019)

We present the design and experimental characterization of a silicon nitride pulse interleaver based on coupled resonator optical waveguide filters.

Zazzi et al. (2023), Optics Express

Highlights the capability of commercial SiN foundries to fabricate ultra-small (7.4 mm × 2 mm), high-resolution, high-throughput AWG spectrographs on a chip suitable for both ground- and space-based telescopes.

Gatkine et al. (2022)

A 8.75 × 3 mm silicon nitride chip with a square waveguide cross-section of 800 × 800 nm is used to fabricate a continuous-output, curved focal-plane photonic Arrayed Waveguide Grating (AWG) with a resolving power of 12,000, a free-spectral range of 18 nm, and a wide operational band of 1425-1650 nm, which allows a continuous sampling of the spectrum in high precision spectroscopy.

Gatkine et al. (2022), SPIE digital library

We discuss the design and demonstration of 4-channel coarse wavelength-division (de-)multiplexers based on cascaded Mach-Zehnder interferometer (MZI) lattice filters and arrayed waveguide gratings (AWG) on a 150 nm silicon nitride ( Si3N4 ) platform.

Stanley Cheung and Michael R.T Tan, Journal of Lightwave Technology (2020)

Low-loss, fabrication-tolerant Si3N4 CWDM lattice filters and AWGs are demonstrated for 990 – 1065nm bottom-emitting VCSELs. Channel separation of 25 nm, XT <; -35 dB and -20 dB are reported with temperature shift of 14.5 pm/°C.

Stanley Cheung and Michael R.T Tan, IEEE Xplore (2020)

We present a hybrid integrated SiN-polymer OPA for realizing an efficient LiDAR. The polymeric modulators are integrated with a SiN power splitter and grating antenna.

Im et al., IEEE (2021)

Microwave-frequency acousto-optic modulation is realized by exciting high-overtone bulk acoustic wave resonances (HBAR) in the photonic stack on a silicon nitride photonic integrated chip. A Si3N4-based optical isolator is demonstrated by spatiotemporal modulation, with over 17 dB isolation achieved.

Tian et al., Nature Communications (2020)

Here we demonstrate InGaAs/InP modified uni-traveling carrier photodiodes on Si3N4 waveguides with 20 nA dark current, 20 GHz bandwidth, and record-high external (internal) responsivities of 0.8 A/W (0.94 A/W) and 0.33 A/W (0.83 A/W) at 1550 nm and 1064 nm, respectively.

Yu et al., Optics Express (2020)

This work demonstrates a heterogeneous platform by bonding lithium niobate (LN) thin films onto a silicon nitride (Si3N4) waveguide layer on silicon.

Chang et al., Optics Letters (2017)

Highlights the capability of commercial SiN foundries to fabricate ultra-small (7.4 mm × 2 mm), high-resolution, high-throughput AWG spectrographs on a chip suitable for both ground- and space-based telescopes.

Gatkine et al. (2022)

A 8.75 × 3 mm silicon nitride chip with a square waveguide cross-section of 800 × 800 nm is used to fabricate a continuous-output, curved focal-plane photonic Arrayed Waveguide Grating (AWG) with a resolving power of 12,000, a free-spectral range of 18 nm, and a wide operational band of 1425-1650 nm, which allows a continuous sampling of the spectrum in high precision spectroscopy.

Gatkine et al. (2022), SPIE digital library

By employing Pound–Drever–Hall locking and a microheater on the silicon nitride microresonator, we show continuous scanning of the soliton comb modes across nearly the full free-spectral range of the microresonator without losing soliton operation, while spectral features with a bandwidth as small as 5 MHz are resolved.

Kuse et al., Optics Letters (2020)

We describe infrared RV spectroscopy at the 10 m Hobby–Eberly Telescope that leverages a 30 GHz electro-optic laser frequency comb with a nanophotonic supercontinuum to calibrate the Habitable Zone Planet Finder spectrograph. The frequency comb generation includes a silicon nitride chip (5  mm×3  mm) on which nanophotonic waveguides are patterned.

Metcalf et al., Optica (2019)

We demonstrate robust frequency-control strategies for near-infrared, octave-bandwidth soliton frequency combs created with nanofabricated silicon nitride ring resonators. The comb links wavelengths between 767 and 1556 nm from a 1064 nm pump laser, and the mode frequencies of the comb are spaced by 1 THz.

Yu et al., Physical Review Applied (2018)

We propose and demonstrate an ultralow-loss Si3N4 racetrack MRR by shaping the mode using a uniform multimode structure to reduce its overlap with the waveguide. The MRR is fabricated by the standard multi project wafer (MPW) foundry process. It consists of two multimode straight waveguides (MSWs) connected by two multimode waveguide bends (MWBs). In particular, the MWBs are based on modified Euler bends, and an MSW directional coupler is used to avoid higher-order mode excitation. In this way, although a multimode waveguide is used in the MRR, only the fundamental mode is excited and transmitted with ultralow loss.

Cui et al. (2023), IEEE

We report on apodized chirped Bragg gratings in a silicon nitride-on-insulator platform. Applications for this device include nonlinear photonics, specifically dispersion compensation in mode-locked lasers operating in the short-wave infrared wavelength band.

Sinobad et al. (2023), CLEO 2023 conference contribution

Here we report spiral microrings as an integrable deformed microcavity designed on silicon nitride-on-silica platform. By fine-adjusting the spacing between two spiral notches, the backscattering strength between clockwise and counterclockwise components can be controlled, which has been revealed in both simulation and experimental results.

Chen et al. (2023), IEEE

In this work we experimentally demonstrate a Si3N4 Photonic Integrated Circuit which offers Row Decoding and RAM addressing functionalities. The passive integrated structure comprises a MRR-based wavelength filtering bank scheme in a 2×4 configuration, which reveals a suppression ratio in the range of 12-25 dB. The performance of the optical circuit has been evaluated in a system-level testbed, where successful addressing in one RAM row has been achieved. Error-free operation has been accomplished for all cases under study, with the whole Row Decoder system’s performance to offer a total power penalty of 2.5 dB.

Simos et al. (2023), JPhys Photonics

In this study, we present an original scalable on-chip parallel IM-DD data transmission system enabled by a single-soliton Kerr microcomb and a reconfigurable microring resonator (MRR)-based dispersion compensator. The highly compact MRR-based Kerr microcomb and dispersion compensator are intrinsically compatible with the parallel processing nature of the WDM link. Besides, the reconfigurability of the dispersion
compensator shows the validation for various data-rate transmissions over multiple single-mode fiber lengths of up to 40 km, with a power consumption of below 160 mW, regardless of the modulation format or of the number of transmission channels utilized.

Lu et al. (2023), Research Square

The Q factor of the specially designed MRR is significantly increased to more than 5 times higher order and reached 10.3 million for the first time.

Cui et al. (2023), IEEE

Highly efficient coupling of light from an optical fiber to silicon nitride (SiN) photonic integrated circuits (PICs) is experimentally demonstrated with simple and fabrication-tolerant grating couplers (GC). Fully etched amorphous silicon gratings are formed on top of foundry-produced SiN PICs in a back-end-of-the-line (BEOL) process, which is compatible with 248 nm deep UV lithography. Metallic back reflectors are introduced to enhance the coupling efficiency.

Kohli et al. (2023), ACS Publications

Here, we report the design, fabrication, and characterization of CMOS-compatible silicon nitride Apodized chirped Bragg gratings (ACGs) operating in the short-wave infrared band.

Sinobad et al. (2023), IEEE

We demonstrate experimentally an integrated Si3N4 photonic 2×4 Row Decoder that utilizes a MRR-based wavelength filtering bank for successfully addressing one out of four RAM rows within an optical RAM bank architecture.

Simos et al. (2023), CLEO 2023 conference contribution

We demonstrate 3×3 and 4×4 Generalized Mach Zehnder Interferometers (GMZI) integrated on the Si3N4 waveguide platform and present their experimental performance as switching and variable power splitting modules. The GMZI structures have been theoretically modelled by means of a transfer matrix model, evaluating also the GMZI spectral response in the case of fabrication errors that may lead to variations in GMZI arm lengths, MMI phase shifts and MMI splitting ratios. Both 3×3 and 4×4 GMZI structures were fabricated as integrated Si3N4-based circuits and were experimentally characterized with the experimental results being in close agreement with the theoretical predictions. They both reveal a resonant spectral behavior with an FSR of 1.9 nm and low average insertion losses per port that were measured to be 1±0.2 and 2.4±0.4 dB. The two GMZI structures were utilized as 1:3 and 1:4 switching elements, respectively, with average crosstalk levels being always greater than 10 dB for all possible input-output port combinations. Finally, their credentials to serve within linear optical circuit implementations were evaluated through their experimental characterization in variable power splitting applications, showing that the power level at a single output port can take any value between 0 and 100% of the input signal.

Kovaios et al. (2023), IEEE Xplore

A compact on-chip optical convolutional processing unit is fabricated on a low-loss silicon nitride platform to demonstrate its capability for large-scale integration. Three 2 × 2 correlated real-valued kernels are made of two multimode interference cells and four phase shifters to perform parallel convolution operations. Although the convolution kernels are interrelated, ten-class classification of handwritten digits from the MNIST database is experimentally demonstrated. The linear scalability of the proposed design with respect to computational size translates into a solid potential for large-scale integration.

Meng et al. (2023), Nature communications

A high-speed plasmonic barium titanate (BTO, BaTiO3) Mach-Zehnder modulator processed onto foundry-produced Silicon nitride (SiN) is presented. We combine nanoscale plasmonics with BTO as solid-state active material and silicon nitride (SiN) for versatile and low loss waveguiding, and integrate them in a monolithic platform. The 15 µm long high-speed modulator features a flat electro-optic frequency response up to 70 GHz and is expected to be flat way beyond. Data experiments reaching 216 Gbit/s with a 216 GBd 2PAM signal and 256 Gbit/s with a 128 GBd 4PAM signal are demonstrated. The merger of the versatile silicon nitride platform with high-speed plasmonics using the highly nonlinear ferroelectric BTO is an attractive solution as a future Tb/s optical interconnect platform.

Kohli et al. (2023), IEEE Xplore

In this work, we present for the first time a 4×4 Generalized Mach Zehnder Interferometer (GMZI) incorporated on a Si3N4 photonic integration platform and we experimentally demonstrate its operation as a variable power splitter.

Kovaios et al. (2023), SPIE digital library

In this work, we demonstrate a monolithic, fully complementary metal-oxide-semiconductor compatible, nonlinear Mach-Zehnder interferometer isolator based on third order optical nonlinearity, which is broadband, low insertion loss and easy to fabricate. In this proof of principle study, we show up to 15 dB isolation with 0.4 dB insertion loss and a device footprint of 0.4 mm2 which can easily be improved on further. Not only can such a device be used for integrated optical systems but also for the fibre based optical systems.

Singh et al. (2023), Optics Express

In this study, we demonstrate a hybrid OPA that capitalizes on a silicon nitride line beam emitter based on tapered waveguides array, which facilitates efficient line beam scanning exhibiting flexible vertical field-of-views (FOVs) at a wavelength of 1550 nm.

Wang et al. (2022), IEEE Xplore

This study proposes and demonstrates a dispersive silicon–nitride OPA that allows for passive wavelength-tuned steering of a line beam with an elongated vertical beamwidth.

Bhandari et al. (2022), Scientific Reports

We fabricated in silicon nitride technology a proof of concept steerer with beam waist 0.36° ×0.175°, addressing a field of view of 15° ×2.8°. A new design iteration is also reported with and 0.24° ×0.16° beam waist and 15° ×11.2° field of view.

Munoz et al. (2022), IEEE Xplore

We propose and demonstrate an optical phased-array-based bidirectional grating antenna (BDGA) in silicon nitride waveguides. The manufactured BDGA could achieve an enhanced beam-steering efficiency of 0.148 deg/nm as well as a stable spectral emission response in the wavelength range of 1530–1600 nm.

Lee et al., Photonics Research (2022)

We present the design of Vernier ring-inspired reflectors based on an 800nm- thick Si3N4 platform providing a TE fundamental mode with an effective index close to 1.71 for a width of 800nm, a group index close to 2.08 at λ=1550nm wavelength, and propagation losses as low as 0.2dB/cm. The proposed thick- Si3N4 designs are based on a simple dual ring Vernier configuration achieving an experimental FSR near 38nm and a 15dB side-mode suppression.

Chatzitheocharis et al., SPIE digital library (2021)

We present a hybrid integrated SiN-polymer OPA for realizing an efficient LiDAR. The polymeric modulators are integrated with a SiN power splitter and grating antenna.

Im et al., IEEE Xplore (2021)

We propose and demonstrate a backward-emitting silicon nitride optical phased arrays (OPA) incorporating a reinforced grating vector, which provides efficient wavelength-tuned beam steering along the longitudinal direction.

Im et al., IEEE Xplore (2020)

We propose a silicon nitride polarization beam splitter that exploits serially cascaded asymmetric directional couplers (ADCs), leading to a high polarization extinction ratio (PER) over a broad bandwidth. The measured transverse-electric and transverse-magnetic PERs were determined to be above 23 dB and 10 dB over an 80-nm bandwidth, respectively, spanning 𝜆=1520−1600nm.

Bhandari et al., Optics Letters (2020)

Here we investigate effects of proton radiation on high-Q (𝒪(10^6)) silicon nitride microresonators formed by a waveguide ring. We show that the irradiation with high-energy protons has no lasting effect on the linear optical losses of the microresonators.

Brasch et al., Optics Express (2014)

Silicon nitride (Si 3 N 4 ) is an excellent material platform for visible wavelength photonic integrated circuits, in particular, as a host for the heterogeneous/hybrid integration of complementary materials. In this work, we characterise the performance of the Si 3 N 4 from LIGENTEC as a base for hybrid integration.

Smith et al., IEEE (2023)

We present a high performance silicon nitride photonic integrated circuit platform operating at visible wavelengths, accessible through the commercial foundry, LIGENTEC. Propagation losses were measured across the visible spectrum from 450 nm to 850 nm.

Smith et al., Optical Materials Express (2023)

Silicon nitride (SiN) photonic integrated circuits (PICs) are promising in visible light applications such as OCT, Cytometry, sensors and light sources. LIGENTEC is introduced as one of the foundries offering open-access generic SiN PICs.

Porcel et al., Science Direct (2018)