Multiple-channel silicon micro-resonator based filters for WDM applications

Shijun Xiao, Purdue University
Maroof H. Khan, Birck Nanotechnology Center, Purdue University
Hao Shen, Birck Nanotechnology Center, Purdue University
Minghao Qi, Birck Nanotechnology Center, Purdue University

Abstract

We demonstrate predictable resonance wavelength shifts in silicon micro-resonators by varying their perimeters using high-resolution lithography. The linear coefficient between the resonance wavelength shifts and the perimeter changes is determined with detailed experiments, and found to be nearly constant across the C and L bands in telecommunications. This empirical coefficient is also compared to that obtained from simulations on straight waveguides. Based on the linear model, without post-fabrication trimming or tuning, an eight-channel wavelength de-multiplexer with reasonably predicted average channel spacing similar to 1.8 +/- 0.1 nm (3dB bandwidth similar to 0.7 +/- 0.1 nm) is demonstrated at telecommunication bands in a silicon chip for the first time. This filter has out-of-band rejection ratio similar to 40 dB, low channel crosstalk <= 30 dB and low channel dropping loss <= +/- 1 dB except for degraded performance in one channel due to fabrication imperfections.