Sub-100 μm Photonic Crystal Si Optical Modulators: Spectral, Athermal, and High-Speed Performance

We report on our recent progress on Si Mach-Zehnder modulators (MZMs) incorporating sub-100 μm slow-light photonic crystal waveguide (PCW) phase-shifters. In the standard MZM with a PCW in each of the arms, we study the power-dependent bit-error-rate (BER) characteristics at 10 Gb/s, and measure BER = 1 × 10^-9 and 1 × 10^-8 even with phase-shifter lengths of 90 and 50 μm, respectively. Furthermore, by exploiting the low-dispersion slow-light in the 90 μm device, we measure a spectral operating bandwidth of 16.9 nm and temperature tolerance between 19-124°C, where the eye pattern amplitude is consistent to within ±25%. In the device with a 90 μm PCW in only one of the MZM arms, designed for large-n_g operation, we achieve BER = 1 × 10^-9 at 10 Gb/s and also observed barely but open eye patterns at 25 and 40 Gb/s.