Column-row addressing of thermo-optic phase shifters for controlling large silicon photonic circuits

We demonstrate a time-multiplexed row-column addressing scheme to drive thermo-optic phase shifters in a silicon photonic circuit. By integrating a diode in series with the heater, we can connect $N \times M$ heaters in an matrix topology to $N$ row and $M$ column lines. The heaters are digitally driven with pulse-width modulation, and time-multiplexed over different channels. This makes it possible to drive the circuit without digital-to-analog converters, and using only $M+N$ wires. We demonstrate this concept with a $1 \times 16$ power splitter tree with 15 thermo-optic phase shifters that are controlled in a $3 \times 5$ matrix, connected through 8 bond pads. This technique is especially useful in silicon photonic circuits with many tuners but limited space for electrical connections

Tutorial : programmable integrated photonics

Programmable photonic circuits are optical chips whose functionality can be (re)configured through electronics and software. This programmability enables new functionality, and opens the path to general-purpose photonic chips, similar to electronic FPGAs. This tutorial discusses the operational principles and technology stack for these chips

Programmable silicon photonic integrated circuits

Programmable photonic circuits offer a new way to explore photonic chips: instead of hardwiring waveguide connections, one programs a mesh of tunable couplers. This requires electronics and software routines to govern the behavior of the chip, making it possible to rapidly develop new photonic applications

Optical leaky fin waveguide for long-range optical antennas on high-index contrast photonic circuit platforms

Long-distance light detection and ranging (LiDAR) applications require an aperture size in the order of 30 mm to project 200–300 m. To generate such collimated Gaussian beams from the surface of a chip, this work presents a novel waveguide antenna concept, which we call an “optical leaky fin antenna,” consisting of a tapered waveguide with a narrow vertical “fin” on top. The proposed structure (operating around =1.55 μm) overcomes fundamental fabrication challenges encountered in weak apodized gratings, the conventional method to create an off-chip wide Gaussian beam from a waveguide chip. We explore the design space of the antenna by scanning the relevant cross section parameters in a mode solver, and their sensitivity is examined. We also investigate the dispersion of the emission pattern and angle with the wavelength. The simulated design space is then used to construct and simulate an optical antenna to emit a collimated target intensity profile. Results show inherent robustness to crucial design parameters and indicate good scalability of the design. Possibilities and challenges to fabricate this device concept are also discussed. This novel antenna concept illustrates the possibility to integrate long optical antennas required for long-range solid-state LiDAR systems on a high-index contrast platform with a scalable fabrication method

General-purpose programmable photonic chips

Photonic chips are becoming more programmable, with connectivity that is reconfigured using electronics and software. This evolution is propelled by artificial intelligence and quantum computing applications. We will discuss more general-purpose circuits that could be deployed in more diverse applications, similar to general-purpose programmable electronics