BJT-Type Optical Phase Shifter with Small Power Consumption and Fast Response Time on a Silicon Photonics Foundry Platform

We demonstrate a novel optical phase shifter with a bipolar junction transistor (BJT) type of device structure based on the silicon photonics foundry platform. By operating such a device in saturation mode, we obtain measured output I_EC-V_EC characteristics very similar to those of an ideal diode, which has a nearly zero turn-on voltage and an extremely small differential resistance. The huge amount of injected current under a small voltage swing (0.1 V) in the operation window makes it possible to obtain significant plasma induced change of the refractive index in the optical waveguide with an extremely small driving-voltage. The device has a small foot-print (500 μm in length), but exhibits small static power consumption for the π phase-shift (P_π: 4.1 mW), reasonable propagation loss (0.02 dB/μm), small driving-voltage (V_π: 0.12 V), fast switching time (rise/fall <1.6/1 ns), a residue amplitude modulation (RAM) as small as 0.18 dB, and a very-low power consumption (0.45 mW) during dynamic operation.