Silicon photonics has experienced phenomenal transformations over the last decade. In this paper, we present some of the notable advances in silicon-based passive and active optical interconnect components, and highlight some of our key contributions. Light is also cast on few other parallel technologies that are working in tandem with silicon-based structures, and providing unique functions not achievable with any single system acting alone. With an increasing utilization of CMOS foundries for silicon photonics fabrication, a viable path for realizing extremely low-cost integrated optoelectronics has been paved. These advances are expected to benefit several application domains in the years to come, including communication networks, sensing, and nonlinear systems.

We demonstrate a through-etched grating coupler based on subwavelength nanostructure. The grating consists of arrays of 80 nm  343 nm rectangular air holes, which can be patterned in a single lithography/etch. A peak coupling efficiency of 59% at 1551.6 nm and a 3 dB bandwidth of 60 nm are achieved utilizing the silicon-on-insulator platform with a 1 lm thick buried-oxide layer for transverse electric mode. The performance is comparable to gratings requiring much more complicated fabrication processes. V

Building on our discovery that mutations in the transmembrane serine protease, TMPRSS3, cause nonsyndromic deafness, we have investigated the contribution of other TMPRSS family members to the auditory function. To identify which of the 16 known TMPRSS genes had a strong likelihood of involvement in hearing function, three types of biological evidence were examined: 1) expression in inner ear tissues; 2) location in a genomic interval that contains a yet unidentified gene for deafness; and 3) evaluation of hearing status of any available Tmprss knockout mouse strains. This analysis demonstrated that, besides TMPRSS3, another TMPRSS gene was essential for hearing and, indeed, mice deficient for Hepsin (Hpn) also known as Tmprss1 exhibited profound hearing loss. In addition, TMPRSS2, TMPRSS5, and CORIN, also named TMPRSS10, showed strong likelihood of involvement based on their inner ear expression and mapping position within deafness loci PKSR7, DFNB24, and DFNB25, respectively. These four TMPRSS genes were then screened for mutations in affected members of the DFNB24 and DFNB25 deafness families, and in a cohort of 362 sporadic deaf cases. This large mutation screen revealed numerous novel sequence variations including three potential pathogenic mutations in the TMPRSS5 gene. The mutant forms of TMPRSS5 showed reduced or absent proteolytic activity. Subsequently, TMPRSS genes with evidence of involvement in deafness were further characterized, and their sites of expression were determined. Tmprss1, 3, and 5 proteins were detected in spiral ganglion neurons. Tmprss3 was also present in the organ of Corti. TMPRSS1 and 3 proteins appeared stably anchored to the endoplasmic reticulum membranes, whereas TMPRSS5 was also detected at the plasma membrane. Collectively, these results provide evidence that TMPRSS1 and TMPRSS3 play and TMPRSS5 may play important and specific roles in hearing.

We present an experimental demonstration of an optical phased array implementation on silicon nanomembrane. The integrated on-chip array configuration is non-uniform and avoids grating lobes inside the field of view during beam steering while allowing the waveguide separation to be large enough to prevent optical coupling. A 1 × 12 multimode interference beam splitter uniformly excites the arrayed waveguides. Individually controllable micro-heaters modulate the optical phase in the arrayed waveguides. A beam steering angle of 10.2° in a silicon planar guide equivalent to an effective steering angle of 31.9° in air is demonstrated at 1.55 μm.

A 16-element optical phased array integrated on chip is presented for achieving two-dimensional (2D) optical beam steering. The device is fabricated on the silicon-on-insulator platform with a 250 nm silicon device layer. Steering is achieved via a combination of wavelength tuning and thermo-optic phase shifting with a switching power of P(π)=20  mW per channel. Using a silicon waveguide grating with a polycrystalline silicon overlay enables narrow far field beam widths while mitigating the precise etching needed for conventional shallow etch gratings. Using this system, 2D steering across a 20°×15° field of view is achieved with a sidelobe level better than 10 dB and with beam widths of 1.2°×0.5°.