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A unique structured carrier depletion ring modulator is fabricated. We achieved high modulation efficiency of 0.9nm with a large extinction ratio of about 20dB. The device has a free spectral range of about 13nm.

A 30-µm length silicon rib-waveguide based on-chip optical attenuator is fabricated and experimentally demonstrated. For a wide range of wavelengths (1490-1590nm), the attenuator offers around 2.6 dB of attenuation at 1.5V.

A very compact ring resonator based multiplexer is demonstrated. The fabricated four channel multiplexer shows the extinction ratio of about 25dB in each of the four consecutive resonances with a channel spacing of 2nm.

With the growing demand for automotive LiDAR and the maturation of silicon photonics platforms, optical phased arrays (OPAs) have emerged as a key technology for solid-state optical beam-steering. In order to meet realistic automotive specifications with OPAs, >500 antenna elements should work reliably under tight power and cost budgets. Existing multi-chip solutions necessitate expensive packaging and assembly to achieve high interconnect density. Even with 2-D monolithic integration, high-voltage drivers to deliver sufficient power to resistive phase shifters typically result in significant overhead in die area and limited power efficiency. In this article, we introduce a single-chip OPA realized through wafer-scale 3-D integration of silicon photonics and CMOS. Flexible and ultra-dense connections with through-oxide vias (TOVs) in our platform resolve the I/O density issue. Moreover, low-voltage L-shaped phase shifters and compact, efficient switch-mode drivers, connected vertically using TOVs, remove wiring/placement overhead and achieve a large active array aperture within a compact die. Our OPA prototype achieves wide-range 2-D steering over 18.5 $^\circ \times $ 16° by leveraging wavelength tuning and phase control, and array scaling up to 125 elements with a large aperture size of $0.5\,\mathrm {mm}\times 0.5\,\mathrm {mm}$ and 0.15 $^\circ \times $ 0.25° beamwidth while consuming 20 mW/element average power. Since our system supports per-element independent phase control, increased sensitivity to process variations in L-shaped shifters is fully compensated by a simple calibration process.

The accuracy of conventional ADCs for high-frequency input signals is mainly limited by the sampling clock jitter. To address this issue, this paper demonstrates an ADC that uses low-jitter $( optical pulses to sample the input signal. A prototype two-channel ADC is realized in a 3D integrated platform with 65 nm CMOS and silicon-photonics connected using high-density TOVs. With optical pulses spaced at 250 ps (4 GS/s effective sampling rate), the ADC achieves SNDR of 40 dB near DC and 37 dB at 45 GHz input.

The realization of a low-cost and robust optical beam-steering platform is a key enabler for a number of applications, including light detection and ranging (LIDAR) and free-space optical communications (FSO). Optical phased arrays (OPAs) have emerged as a promising solution, due to advancements in photonic integrated circuits (PIC) foundry processes, which have enabled high-precision fabrication of PICs with a large number of components [1]–[3]. In order to meet steering range and directivity requirements in systems such as autonomous vehicles, a clear path to scaling OPAs to millimeter-scale apertures with thousands of tight-pitched antenna elements is critical. As the element count grows, independent phase control for each element becomes crucial since maintaining coherence between elements becomes more difficult due to process variations. Moreover, independent control allows for unique system capabilities, such as multi-beam formation and converging/adaptive beams, which makes OPAs a particularly attractive solid-state beamforming technology.