PSS/Si hybrid photodetector.

Photonic integrated Raman lasers have extended the wavelength range of chip-scale laser sources and have enabled applications including molecular spectroscopy, environmental analysis, and biological detection. Yet, the performance is strongly determined by the pumping condition and Raman shift value of nonlinear medias, leaving challenges to have a widely and continuously tunable Raman laser (e.g., over 100 nm). Here, photonic engineered Raman lasers based on chip-integrated chalcogenide microresonators are demonstrated. The home-developed chalcogenide photonic platform is of high nonlinearity, wide transparency, and low loss. The strong and broadband material Raman response has promised rich dynamics of Raman lasing. Indeed, both single-mode Raman lasing and a broadband Raman-Kerr comb, which are found engineered by tuning the dispersion of the chalcogenide microresonator, are demonstrated. The single-mode Raman laser, together with its cascaded modes, supports a gap-free tuning range over 140 nm, while the threshold power is as low as 3.25 mW. The results may contribute to the understanding of Raman and Kerr nonlinear interactions in dissipative and nonlinear microresonators, and on application aspect, may pave a way to integrated and efficient laser sources that is desired in spectroscopic applications in the infrared.

Chalcogenide glass (ChG) is an attractive material for highly efficient nonlinear photonics, which can cover an ultrabroadband wavelength window from the near-visible to the footprint infrared region. However, it remains a challenge to implement highly-efficient and low-threshold optical parametric processes in chip-scale ChG devices due to thermal and light-induced instabilities as well as a high-loss factor in ChG films. Here, we develop a systematic fabrication process for high-performance photonic-chip-integrated ChG devices, by which planar-integrated ChG microresonators with an intrinsic quality ( Q ) factor above 1 million are demonstrated. In particular, an in situ light-induced annealing method is introduced to overcome the longstanding instability underlying ChG film. In high- Q ChG microresonators, optical parametric oscillations with threshold power as low as 5.4 mW are demonstrated for the first time, to our best knowledge. Our results would contribute to efforts of making efficient and low-threshold optical microcombs not only in the near-infrared as presented but more promisingly in the midinfrared range.

Integrated nonlinear photonics, combined nonlinear optics with state‐of‐the‐art photonic integration, play a crucial role in chip‐integrated technologies including optical frequency combs, molecular spectroscopy, and quantum optics. Optical materials with favorable properties are the foundation to promote integrated photonic devices with bandwidth, efficiency, and flexibility in high‐volume chip‐scale fabrication. In this work, a newly developed chalcogenide glass‐Ge25Sb10S65 (GeSbS) is presented for nonlinear photonic integration and for dissipative soliton microcomb generation. The GeSbS features wide transparency (0.5–10 µm), strong nonlinearity (1.3 × 10−18 m2 W−1), and low thermo‐refractive coefficient (3.1 × 10−5 K−1), and is complementary metal oxide semiconductor (CMOS)‐compatible in fabrication. In this platform, chip‐integrated optical microresonators with an average intrinsic quality (Q) factor of ≈1.97 × 106 are implemented, and lithographically controlled dispersion engineering is carried out. In particular, both a bright soliton‐based microcomb with bandwidth of 240 nm (≈1440–1680 nm) and a dark‐pulse comb with bandwidth of 80 nm (≈1510–1590 nm) are generated in a single microresonator in its separated fundamental polarized mode families.The ten‐milliwatt level of soliton microcomb operation power facilitates the monolithically integrated photonic circuits.  The results provide a potential material platform for integrated nonlinear photonics for highly compact and high‐intensity nonlinear interactions in visible and infrared regions.

In this work, on-chip chalcogenide glass photonic integrations with several fundamental photonic building blocks are designed and fabricated based on the As 2 S 3 platform for improved 2 μm optical interconnection, achieving a broadened wavelength bandwidth and improved fabrication tolerance. A 600 nm thick As 2 S 3 strip waveguide has low propagation loss of 1.447 dB/cm at 2 μm. Broadband vertical coupling is realized by a grating coupler with 4.3 dB coupling loss. A Bragg grating filter, power splitter, Mach–Zander interferometer, and mode converter for on-chip mode division multiplexing (MDM) are also reported at 2 μm with reliable performances. Finally, a record high MDM optical interconnection capacity of 3 × 80    Gbps at 2 μm is experimentally demonstrated based on the proposed As 2 S 3 chip, drawing promising prospects for future photonic integration and high-speed interconnection at the 2 μm waveband.