High-speed compact silicon photonic Michelson interferometric modulator

Abstract

We present the detailed analysis and characterization of a silicon Michelson modulator with short 500 μm phase shifters and a low VπLπ of 0.72 V-cm under reverse bias. We investigate optical modulation of reverse biased p-n and forward biased p-i-n junctions. We demonstrate for the first time that error-free operation up to 40 Gbps is possible with lumped silicon interferometric modulators. For reverse bias operation, we show that even greater bandwidth can be obtained with lower impedance drivers. Forward bias operation with pre-emphasized signals is shown to have clean eye diagrams up to 40 Gbps, however, error counting reveals a strong dependence on test patterns and that error-free operation is achievable for short pattern lengths.

Low-loss high-extinction-ratio single-drive push-pull silicon Michelson interferometric modulator

“…The total fiber-tofiber IL is 8 dB, including ∼3 dB on-chip IL and ∼2.5 dB input/output coupling loss. The on-chip IL is much lower than the values reported in the previous MIMs [15,16] . The free spectral range (FSR) of the interference fringe is 3.22 nm and the static ER exceeds 30 dB.…”

“…To lower the IL of MZMs, the doping concentrations of the PN junctions should be reduced, but inevitably at the expense of a lower modulation depth. To obtain a high modulation depth without increasing the physical length of active arms, silicon Michelson interferometer (MI)-based modulators (MIMs) have been proposed [15,16] . In the MIMs, the propagating light makes a round trip along the phase-shifting waveguides, and thus the RF signal interacts with both the forward and backward light, resulting in enhanced modulation efficiency as well as a more compact device.…”

“…As depicted in Refs. [15,16], the phase shift is expressed as Δφ ¼ 2πΔλ∕FSR, where Δλ is the wavelength shift of the spectral notch. It can be observed that the phase shift increases more slowly when the reverse bias becomes larger.…”

“…5(b), at the received optical power of −10.65 dBm, a clear constellation diagram was observed with a Q-factor of 5.89, a dynamic IL of 2.5 dB, and an error vector magnitude (EVM) of 25.8% including a 25.2% magnitude error and a 3.5% phase error. The high magnitude error can be reduced by using pre-emphasis or equalization on the RF drive signal where the high-frequency response can be enhanced [16] . The bit error rate (BER) was measured to be 1.1 × 10 −11 .…”

Dual phase-shift Bragg grating silicon photonic modulator operating up to 60 Gb/s

“…In addition to MZMs and MRMs, other integrated SiP modulator structures, such as Michelson interferometric modulators (MIM) [16,17], have been successfully developed to achieve efficient modulation, using a lumped-element electrode, by exploiting the fact that the light travels twice through the PN junction phase-shifter. However, until now, little effort has been devoted to develop integrated Bragg grating (IBG) modulators.…”