Si Photonic Crystal Slow-Light Modulators with Periodic p–n Junctions

We theoretically optimized and demonstrated the periodic p-n junction in silicon photonic crystal slow-light modulators to balance the efficiency and speed of phase shifters and reduce the power consumption compared with those of previous linear and interleaved p-n junctions. In particular, sawtooth and wavy junctions, whose profiles match with the distribution of the slow-light mode, theoretically prove effective in achieving these objectives. However, the sawtooth junction requires a high-resolution process. Therefore, we finally employed the wavy junction and obtained 25- and 32-Gb/s operations in a 200-μm device with extinction ratios of 4 and 3 dB, respectively, for an excess modulation loss of 1 dB.