Publications Details

Active wavelength control of silicon microphotonic resonant modulators

Lentine, Anthony L.; Zortman, W.A.; Trotter, D.C.; Watts, Michael R.

We present simulations and preliminary experimental results of a new method to stabilize the resonant wavelength of an optical resonant modulator using bit error rate measurements from a local receiver to drive an integrated microheater. Optical interconnections have the potential to significantly reduce the power dissipation and greatly increase the aggregate connection bandwidth in high performance multiprocessor digital computers, intra-satellite communications, and data centers. Silicon photonic micro-ring and micro-disk modulators for the transmit side of the links are an active area of research, because of they are compatible with silicon electronics processing and have been demonstrated at data rates above 10 Gb/s and at sub 100fJ/bit switching energies [1-3]. However, a key problem that remains to be solved for these devices is control of their optical wavelength that varies as a function of fabrication tolerances (thicknesses and dimensions) and temperature. In [4], a heater and sensor were integrated with a modulator to stabilize its wavelength, but the method demonstrated suffers the potential drawbacks of aging of the sensor over time and the potential need to pre-calibrate every sensor/modulator. Here, we present a new method of tuning the resonant wavelength of the device to match the incident light's wavelength using independent logic one and logic zero bit errors from a local receiver and simple logic circuitry to drive an integrated micro-heater to adjust the temperature of the device. Simulations of the control loop show it to be robust to the choice of gain, receiver decision threshold, and starting point temperature. Preliminary experimental results using an integrated microresonant heater modulator device [5] operating at 3.125 Gb/s with an FPGA and external reciver driving the control loop show a tuning range of 25C-32C (>2 nm shift). No dithering or calibration is required; the technique is not susceptible to sensor aging, and it can compensate for long-term drift in the characteristics of the modulator. © 2012 IEEE.