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We demonstrated low-temperature bonding of III–V InP-based compound semiconductor on silicon via nano-thin SiO2 interlayer down to thickness of 20 nm, with ultra-smooth surface for heterogeneous photonic integration. The bonding is achieved with chemical cleaning of the sample surface, followed by oxygen plasma surface activation, which gives high quality bonding between the two different materials. Detail analyses on the bonded samples are carried out. From the photoluminescence and the x-ray diffraction measurements, in which no significant peak shift and peak broadening are observed, we conclude that the crystalline quality of the bonded thin film is preserved. The cross-sectional high resolution transmission electron microscopy shows that bonded III–V-SiO2–Si interface has no observable defect. These results reinforce that the proposed bonding offers a promising technology for realizing versatile heterogeneous photonics integration.

Heterogeneous III-V/Si integration with a compact optical vertical interconnect access is fabricated and the light coupling efficiency between the III-V/Si waveguide and the silicon nanophotonic waveguide is characterized. The III-V semiconductor material is directly bonded to the silicon-on-insulator (SOI) substrate and etched to form the III-V/Si waveguide for a higher light confinement in the active region. The compact optical vertical interconnect access is formed through tapering a III-V and an SOI layer in the same direction. The measured III-V/Si waveguide has a light coupling efficiency above ~90% to the silicon photonic layer with the tapering structure. This heterogeneous and light coupling structure can provide an efficient platform for photonic systems on chip, including passive and active devices.

A new heterogeneous Si/III-V integration and the optical vertical interconnect access to the silicon-on-insulator (SOI) nanophotonic layer is proposed and designed. The III-V semiconductor layers are directly bonded to the SOI layer and etched to form the Si/III-V waveguide (after removal of the substrate), which has no air-trench or SOI channel waveguide underneath as the prior art. The design example shows a 1.5 μm wide Si/III-V waveguide has a confinement factor of ~24% in a 100 nm-thick active region for effective light amplification/absorption. The optical vertical interconnect access is realized through tapering both the III-V semiconductor waveguide and SOI layer in the same direction. Optimization using a simple approximated two-dimensional modal presented gives ~100% coupling efficiency with a 25 μm long optical vertical interconnect access. A three-dimensional finite-difference-time-domain electromagnetic simulation verifies the design numerically and also shows the proposed structure has a good alignment tolerance for fabrication.

Patterned gallium nitride nanowires have been grown on n-Si(100) substrates by pulsed laser ablation. The nanowires are patterned using a physical mask, resulting in regions of nanowire growth of different density. These gallium nitride nanowires are single-crystalline with hexagonal wurzite structures. The electrical transport measurements of individual GaN nanowires show near-linear current–voltage characteristics. The estimated electron densities of these individual GaN nanowires range from 1.8–6.8 × 1018 cm−3. The field emission characteristics of these patterned gallium nitride nanowires show a turn-on field of 8.4 V µm−1 to achieve a current density of 0.01 mA cm−2 and an enhanced field emission current density as high as 0.96 mA cm−2 at an applied field of 10.8 V µm−1. The field emission results indicate that, besides crystalline quality as well as the low electron affinity of gallium nitride, density difference in the nanowires growth greatly enhances their field emission properties by reducing the screening between nanowires.

We fabricated highly-nonlinear (550W−1 m−1) and low loss ultra-rich silicon nitride waveguides that can achieve parametric wavelength conversion over 170nm and parametric amplification of 23dB.

We report the design and experimental results of an electrically pumped Silicon/AlGaInAs evanescent laser with right-angled-wedge reflector defined in the silicon layer. A continuous-wave laser with a lasing threshold current density of 2.8kA/cm2 is achieved.

Spectral tunability methods used in optical communications and signal processing leveraging optical, electrical, and acousto-optic effects typically involve spectral truncation that results in energy loss. Here we demonstrate temperature tunable spectral broadening using a nonlinear ultra-silicon-rich nitride device consisting of a 3-mm-long cladding-modulated Bragg grating and a 7-mm-long nonlinear channel waveguide. By operating at frequencies close to the grating band edge, in an apodized Bragg grating, we access strong grating-induced dispersion while maintaining low losses and high transmissivity. We further exploit the redshift in the Bragg grating stopband due to the thermo-optic effect to achieve tunable dispersion, leading to varying degrees of soliton-effect compression and self-phase-modulation-induced spectral broadening. We observe an increase in the bandwidth of the output pulse spectrum from 69 to 106 nm as temperature decreases from 70 degrees C to 25 degrees C, in good agreement with simulated results using the generalized nonlinear Schrodinger equation. The demonstrated approach provides a new avenue to achieve on-chip laser spectral tuning without loss in pulse energy. (C) 2021 Chinese Laser Press

We have demonstrated a heterogeneously integrated Si/III-V laser based on an ultra-large-angle super-compact curved diffraction grating suitable for WDM applications in EPICs The lasing threshold is 150mA giving a maximum output power of 2.35mW.