Design of low bias voltage Ge/SiGe multiple quantum wells electro-absorption modulator at 1550 nm

We design and simulate a Ge/SiGe multiple quantum wells (MQWs) modulator based on quantum confined Stark effect (QCSE) that operates at 1550 nm. By introducing a thick well and thin barrier in multiple quantum wells structure, the compressive strain of the Ge well is reduced and the absorption edge is shifted to the longer wavelength. An 8-band k⋅p model is employed to calculate the eigenstates and absorption spectra, and influences of quantum well parameters on the absorption property is analyzed and discussed. The numerical simulation indicates that the bias voltage is remarkably reduced to 0.5 V with 1 V voltage swing for 10 wells, while still maintaining over 5 dB absorption contrast ratio. The proposed Ge/SiGe modulator can be a potential approach compatible with traditional complementary metal-oxide-semiconductor (CMOS) technology and adoptable for integration with electronic components.