Advances Toward Ge/SiGe Quantum-Well Waveguide Modulators at 1.3μm

Abstract

The paper reports on the developments of Ge/SiGe quantum well (QW) waveguide modulators operating at 1.3 μm. Two modulator configurations have been studied: The first one is based on QW structures grown on a 13-μm SiGe buffer on bulk silicon. Light was directly coupled and propagated in Ge/ Si 0 .35 Ge 0 .65 QWs. Using a 3-μm-wide and 50-μm-long modulator, an extinction ratio (ER) up to 6 dB was obtained at 1.3 μm. In the second configuration, the aim is to integrate Ge/SiGe QW on standard silicon-on-insulator (SOI) waveguides. A reduction of buffer thickness is then required to allow the light coupling from Si waveguide to Ge/SiGe QW. To this purpose, first we demonstrated QCSE with a thin (360-nm-thick) Si 0 .08 Ge 0 .92 buffer on silicon using the well-known Ge/Si 0 .15 Ge 0 .85 QWs (operated at a wavelength of 1.4 μm). Based on these promising experimental results, we theoretically investigated properties of a Ge/Si 0 .65 Ge 0 .35 QW modulator integrated on SOI waveguides. 7.7 dB ER were predicted with 4 dB optical insertion loss and an estimated energy consumption of 59 fJ/bit for a modulator length as short as 69 μm.Index Terms-Modulation, quantum wells, Ge/SiGe, waveguide integration.

Ge-on-Si photonic devices for photonic-electronic integration on a Si platform

“…For the integration with Si WGs, the thickness of relaxed SiGe buffer layer beneath the Ge/GeSi quantum wells should be reduced [84]. The operation at shorter wavelengths around 1.3 µm could be obtained with a precise control of Ge well thickness [86,87].…”

Recent Progress on Ge/SiGe Quantum Well Optical Modulators, Detectors, and Emitters for Optical Interconnects

“…Lever et al [51] and Rouifed et al [52] experimentally reported QCSE from photocurrent measurements around the optical wavelength of 1.3 µm using a similar structure of strain-balanced Ge/SiGe MQWs on Si 0.22 Ge 0.78 and Si 0.21 Ge 0.79 relaxed buffers, respectively. In 2014, Rouifed et al [53] experimentally reported a 3-µm-wide and 50-µm-long Ge/SiGe MQW optical modulator operating in the O-band telecommunication wavelength. The modulator exhibited a 5-dB ER with 4-dB IL for a voltage swing of 3 V between 4 and 7 V at the optical wavelength of~1295 nm.…”

Silicon photonics based on Ge/SiGe quantum well structures

“…Such integration requires a reduction of the thickness of the buffer layer between Ge/SiGe QW and silicon wafer. To this purpose, we developed a relaxed buffer with 360nm thickness that would practically allow the optical coupling between a SOI waveguide and the Ge/SiGe QW active region [9]. We then theoretically investigated properties of a QW modulator integrated on SOI waveguides.…”