Optical Phase Modulators Based on Reverse-Biased III-V/Si Hybrid Metal-Oxide-Semiconductor Capacitors

We present an efficient optical modulator with reverse-biased III-V/Si hybrid metal-oxide-semiconductor (MOS) optical phase shifters. By applying a reverse bias on a III-V/Si hybrid MOS capacitor, we found that the Franz-Keldysh effect and carrier depletion contribute to an efficient optical phase m...

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Bibliographic Details
Published in:IEEE photonics technology letters 2020-03, Vol.32 (6), p.345-348
Main Authors: Li, Qiang, Ho, Chong Pei, Takagi, Shinichi, Takenaka, Mitsuru
Format: Article
Language:English
Subjects:
Bandwidths
Capacitance
Capacitors
Depletion
Doping
Electrooptic modulators
Energy consumption
Franz–Keldysh effect
free-carrier plasma dispersion effect
Group III-V semiconductors
High-speed optical techniques
III-V/Si photonic devices
Metal oxide semiconductors
Modulators
Optical modulation
Optical refraction
Optical variables control
Phase modulation
Phase shifters
Silicon
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Summary:We present an efficient optical modulator with reverse-biased III-V/Si hybrid metal-oxide-semiconductor (MOS) optical phase shifters. By applying a reverse bias on a III-V/Si hybrid MOS capacitor, we found that the Franz-Keldysh effect and carrier depletion contribute to an efficient optical phase modulation. Compared with forward-biased MOS-type optical modulators based on carrier accumulation, the reverse-biased III-V/Si hybrid MOS capacitor shows a small depletion capacitance, which improves the trade-off relationship between modulation bandwidth and energy consumption. We have numerically analyzed the proposed optical modulator in terms of wavelength detuning as well as doping concentrations in the Si and III-V layers. After carefully tuning the doping concentration in Si and III-V layers, a small V_{\pi }L of 0.17 Vcm with a modulation bandwidth of above 200 GHz was predicted. We also experimentally demonstrated the proposed optical modulator that exhibited a V_{\pi }L of 0.12 Vcm. The reverse-biased III-V/Si hybrid MOS optical modulator showed a capacitance half that of the forward-biased III-V/Si hybrid MOS optical modulator with a comparable modulation efficiency, resulting in the enhancement of the modulation bandwidth by a factor of two with the energy per bit reduced by half.
ISSN:1041-1135
1941-0174
DOI:10.1109/LPT.2020.2973174