Ari Novack

Low power 50 Gb/s silicon traveling wave Mach-Zehnder modulator near 1300 nm

A silicon traveling-wave Mach-Zehnder modulator near 1300 nm is demonstrated to operate at 50 Gb/s with a differential 2 Vpp signal at 0 V reverse bias, achieving a 800 fJ/bit power consumption.

Ultralow loss single layer submicron silicon waveguide crossing for SOI optical interconnect

We demonstrate compact, broadband, ultralow loss silicon waveguide crossings operating at 1550 nm and 1310 nm. Cross-wafer measurement of 30 dies shows transmission insertion loss of - 0.028 ± 0.009 dB for the 1550 nm device and - 0.017 ± 0.005 dB for the 1310 nm device. Both crossings show crosstalk lower than - 37 dB. The devices were fabricated in a CMOS-compatible process using 248 nm optical lithography with a single etch step.

Silicon Photonics: The Next Fabless Semiconductor Industry

Something very surprising has been happening in photonics recently: the same foundries and processes that were developed to build transistors are being repurposed to build chips that can generate, detect, modulate, and otherwise manipulate light. This is pretty counterintuitive, since the electronics industry spends billions of dollars to develop tools, processes, and facilities that lend themselves to building the very best transistors without any thought about how to make these processes compatible with photonics (with the obvious exception of the processes designed to make CMOS and CCD camera chips).

Germanium photodetector with 60 GHz bandwidth using inductive gain peaking

Germanium-on-silicon photodetectors have been heavily investigated in recent years as a key component of CMOS-compatible integrated photonics platforms. It has previously been shown that detector bandwidths could theoretically be greatly increased with the incorporation of a carefully chosen inductor and capacitor in the photodetector circuit. Here, we show the experimental results of such a circuit that doubles the detector 3dB bandwidth to 60 GHz. These results suggest that gain peaking is a generally applicable tool for increasing detector bandwidth in practical photonics systems without requiring the difficult process of lowering detector capacitance.

The Road to Affordable, Large-Scale Silicon Photonics

Large-scale optical systems in silicon can become a reality by building upon the existing infrastructure. Due to the shifting economics of silicon photonics, some cost-effective fabless silicon products may even emerge over the next several years.

CMOS-compatible highly efficient polarization splitter and rotator based on a double-etched directional coupler

We present a highly efficient polarization splitter and rotator (PSR), fabricated using 248 nm deep ultraviolet lithography on a silicon-on-insulator substrate. The PSR is based on a double-etched directional coupler with a length of 27 µm. The fabricated PSR yields a TM-to-TE conversion loss better than 0.5 dB and TE insertion loss better than 0.3 dB, with an ultra-low crosstalk (-20 dB) in the wavelength regime 1540-1570 nm.

A single adiabatic microring-based laser in 220 nm silicon-on-insulator

We demonstrate a laser for the silicon photonics platform by hybrid integration with a III/V reflective semiconductor optical amplifier coupled to a 220 nm silicon-on-insulator half-cavity. We utilize a novel ultra-thin silicon edge coupler. A single adiabatic microring based inline reflector is used to select a lasing mode, as compared to the multiple rings and Bragg gratings used in many previous results. Despite the simplified design, the laser was measured to have on-chip 9.8 mW power, less than 220 KHz linewidth, over 45 dB side mode suppression ratio, less than -135 dB/Hz relative intensity noise, and 2.7% wall plug efficiency.

Ultracompact silicon-on-insulator polarization rotator for polarization-diversified circuits.

We present an ultracompact (15.3 μm long) and high-efficiency silicon-on-insulator polarization rotator designed for polarization-diversified circuits. The rotator is comprised of a bilevel-tapered TM0-to-TE1 mode converter and a novel bent-tapered TE1-to-TE0 mode converter. The rotator has a simulated polarization conversion loss lower than 0.2 dB and a polarization-extinction ratio larger than 25 dB over a wavelength range of 80 nm around 1550 nm. The rotator has a SiO2 top-cladding and can be fabricated in a CMOS-compatible process.

High-Efficiency Low-Crosstalk 1310-nm Polarization Splitter and Rotator

We demonstrate the first example of a polarization splitter and rotator (PSR) at 1310 nm built on a silicon-on-insulator platform using 248-nm deep-ultraviolet lithography. The PSR is constructed with a directional coupler, a bilevel taper-based TM0-to-TE1 mode converter, and an asymmetric Mach-Zehnder-based TE1-to-TE0 mode converter. A worst-case TM0-to-TE0 mode-conversion loss of 2 dB, with polarization crosstalk lower than -20 dB over a wide bandwidth of 40 nm is experimentally demonstrated. The worst-case polarization-dependent loss is 0.76 dB.

A compact bi-wavelength polarization splitting grating coupler fabricated in a 220 nm SOI platform.

We experimentally demonstrate a polarization splitting grating coupler that is operational near 1310 nm and 1550 nm in a silicon-on-insulator platform, using the same fiber angle for both wavelength bands. At 1550 nm, the device has an insertion loss of 7.1 dB and a 1.5-dB transmission window of 35 nm. At 1310 nm, the insertion loss and 1.5-dB transmission window are 8.2 dB and 18 nm, respectively. Polarization isolation at 1550 nm is 24 dB. This is the first experimental demonstration of a bi-wavelength polarization-splitting grating coupler.