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We demonstrate a complementary metal–oxide–semiconductor (CMOS)-compatible optical parametric Bragg amplifier on an ultra-silicon-rich nitride chip. The amplifier design incorporates advantageous group index properties in a nonlinear Bragg grating to circumvent phase matching limitations arising from the bulk material and waveguide dispersion. The grating structure further augments the effective nonlinear parameter of 800 W−1/m, considerably lowering the power required for the observation of strong parametric gain. On/off optical parametric gain of 20 dB is achieved using a low peak power of 1.6 W, in good agreement with numerical calculations. This represents a 7 dB improvement in the parametric gain compared to the absence of grating enhancement which is attributed to the Bragg grating induced superior phase matching.

Nonlinear propagation in periodic media has been studied for decades, yielding demonstrations of numerous phenomena including strong temporal compression and slow light generation. Gap solitons, that propagate at frequencies inside the stopband, have been observed in optical fibres but have been elusive in photonic chips. In this manuscript, we investigate nonlinear pulse propagation in a chip-based nonlinear Bragg grating at frequencies inside the stopband and observe clear, unequivocal signatures of gap soliton propagation, including slow light, intensity-dependent transmission, intensity-dependent temporal delay and gap soliton compression. Our experiments which are performed in an on-chip ultra-silicon-rich nitride (USRN) Bragg grating with picosecond time scales, reveal slow light group velocity reduction to 35%–40% of the speed of light in vacuum, change in the temporal delay of 7 ps at low peak powers between 15.7 W–36.6 W, which is accompanied by up to 2.7× temporal compression of input pulses. Theoretical calculations using the nonlinear coupled mode equations confirm the observations of intensity-dependent temporal delay. Of fundamental importance, this demonstration opens up on-chip platforms for novel experimental studies of gap solitons as the basis of all-optical buffers, delay lines and optical storage. [ABSTRACT FROM AUTHOR]

The generation of optical pulse trains from continuous-wave light has attracted growing attention in recent years because it provides a simple way to obtain high repetition rate ultrashort pulses. While pulse generation has been extensively demonstrated in optical fibers, pulse train generation from weak, continuous wave light in photonic chips has posed significant challenges because of the short interaction length and therefore difficulty in acquiring sufficient new frequency content, and/or absence of the appropriate dispersion environment. In this manuscript, we report the pulse train generation of a low continuous-wave signal to 18 ps, by leveraging cross-phase modulation induced by co-propagating pump pulses with a peak power of 3.7 W in an ultra-silicon-rich nitride grating. The pulse train generation dynamics are documented both experimentally and theoretically to arise from cross-phase modulation-induced generation of new spectral content, and dispersive re-phasing. This is a new approach in which picosecond pulse generation may be achieved from low power, continuous-wave light. [ABSTRACT FROM AUTHOR]

Photonic building blocks fabricated using two‐photon polymerization laser lithography are reported. 3D polymer structures are fabricated using a direct laser writing process with nonlinear two‐photon absorption in photosensitive material. The 3D photonic structures include 3D photonic waveguides, Bragg gratings, and resonators. In particular, high‐quality spiral and air‐bridge waveguides providing 3D light guiding beyond a single plane are demonstrated. Sub‐micrometer features as well as unique coupling interfaces with 1.6 dB coupling losses and large 3 dB bandwidth are also demonstrated. Experimental characterization reveals the good transmission performance of the fabricated photonic devices. In addition, the waveguides are demonstrated to support 30 Gb s−1 NRZ (nonreturn to zero) and 56 Gb s−1 PAM4 (pulse amplitude modulation 4) high‐speed data. Small power penalties of 0.7 dB for NRZ (BER = 10−12) and 1.5 dB for PAM4 (BER = 10−6) are obtained. [ABSTRACT FROM AUTHOR]

Bragg Solitons – Historical and Future PerspectivesIn article number 2300373, Dawn T. H. Tan and Benjamin J. Eggleton review the history of Bragg solitons, followed by recent progress made in integrated photonic devices, facilitated by recent advancements in the design and fabrication of on‐chip Bragg gratings. They further discuss the future outlook and their application towards amplifiers, optical storage, low loss delay lines, temporal compression systems, Bragg soliton lasers, and high‐speed communications..By Dawn T. H. Tan and Benjamin J. EggletonReported by Author; Author [Extracted from the article]

Higher‐order soliton dynamics, specifically soliton compression and fission, underpin crucial applications in ultrafast optics, communications, and signal processing. Bragg solitons exploit the strong dispersive properties of periodic media near the photonic band edge. This enables soliton dynamics to occur in very short propagation distances, opening avenues to harness soliton compression and fission in integrated photonic platforms. However, implementation in complementary metal‐oxide semiconductor (CMOS)‐compatible platforms has been hindered by the strong nonlinear loss that dominates the propagation in silicon and the low‐optical nonlinearity of traditional silicon nitride. Here, CMOS‐compatible, on‐chip Bragg solitons, are presented with a soliton‐effect pulse compression with a factor of × 5.7, along with time‐resolved measurements of soliton fission on a CMOS‐compatible photonic circuit platform. These observations are enabled by the combination of a unique cladding‐modulated Bragg grating design and the high nonlinearity and negligible nonlinear loss of compositionally engineered ultra‐silicon‐rich nitride (USRN: Si7N3). [ABSTRACT FROM AUTHOR]