Yongqiang Wei

Silicon/III-V laser with super-compact diffraction grating for WDM applications in electronic-photonic integrated circuits.

We have demonstrated a heterogeneously integrated III-V-on-Silicon laser based on an ultra-large-angle super-compact grating (SCG). The SCG enables single-wavelength operation due to its high-spectral-resolution aberration-free design, enabling wavelength division multiplexing (WDM) applications in Electronic-Photonic Integrated Circuits (EPICs). The SCG based Si/III-V laser is realized by fabricating the SCG on silicon-on-insulator (SOI) substrate. Optical gain is provided by electrically pumped heterogeneous integrated III-V material on silicon. Single-wavelength lasing at 1550 nm with an output power of over 2 mW and a lasing threshold of around 150 mA were achieved.

Heterogeneous Si/III-V integration and the optical vertical interconnect access

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.

Demonstration of heterogeneous III–V/Si integration with a compact optical vertical interconnect access

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.

Electrically pumped heterogeneously integrated Si/III-V evanescent lasers with micro-loop mirror reflector

An electrically pumped heterogeneously integrated Si/AlGaInAs evanescent laser with micro-loop mirror (MLM) as high reflectors at both ends is experimentally demonstrated. Finite-difference time-domain simulation shows that 98% reflectivity can be achieved with micro-loop mirror formed by single-mode silicon-on-insulator (SOI) waveguides. The laser based on a Si/III-V hybrid gain waveguide and passive SOI MLM reflectors is fabricated and single-mode continuous-wave (CW) lasing is achieved at room temperature with a lasing threshold current density of 2.5 kA/cm2.

Fabrication of high-efficiency heterogeneous Si/III-V integration with short optical vertical interconnect access

Silicon nanophotonic platform based on a silicon-on-insulator substrate enables dense photonic integration due to transparency for light propagation and ultra-high refractive index contrast for light confinement. Here, we integrate silicon together with III-V for high-efficiency heterogeneous Silicon/III-V and short vertical optical interconnect access. The fabrication involves 3 critical processes: 1) obtaining more than 80% maximum bonded areas of Si with III-V, 2) precise alignment of III-V nano-devices on top of the passive devices and 3) vertical sidewall etch profile of Si and III-V devices. The measurement results show around 90% coupling efficiency. The realization of this heterogeneous Si/III-V integration platform will open up enormous opportunities for photonic system on silicon through integrating various devices.

Electronic-Nanophotonic Integration

Nanophotonic integration of III-V on silicon based on top-down coupling is presented. Light can be coupled up for amplification/absorption or coupled down for passive processing. Interlayer wafer bonding for this integration is described.