Low-loss silicon optical modulator using doping compensation method at 2 μm wavelength band

Compared with the optical modulator based on 1310 nm and 1550 nm wavelength band, the silicon-based modulator at 2 μm band has a higher absorption loss, since the free carrier effect is more significant in the 2 μm band. In this paper, we demonstrate an optical modulator at 2 μm wavelength band, using a doping compensation method. We reduce absorption loss and keep the modulation extinction ratio at a high level through optimizing waveguide width, PN junction offset and compensated area. With doping compensation, the modulator has an absorption loss by PN junction of 2.8 dB/cm at 0 V and an extinction ratio of 14.2 dB at bitrates of 40 Gb/s.