High-speed Si/GeSi hetero-structure Electro Absorption Modulator

Abstract

The ever-increasing demand for integrated, low power interconnect systems is pushing the bandwidth density of CMOS photonic devices. Taking advantage of the strong Franz-Keldysh effect in the C and L communication bands, electro-absorption modulators in Ge and GeSi are setting a new standard in terms of device footprint and power consumption for next generation photonics interconnect arrays. In this paper, we present a compact, low power electro-absorption modulator (EAM) Si/GeSi hetero-structure based on an 800 nm SOI overlayer with a modulation bandwidth of 56 GHz. The device design and fabrication tolerant process are presented, followed by the measurement analysis. Eye diagram measurements show a dynamic ER of 5.2 dB at a data rate of 56 Gb/s at 1566 nm, and calculated modulator power is 44 fJ/bit.

Strain-enabled ultra-broadband Ge-based photonic devices for low-cost integration in PICs

“…This is because, besides ER, IL also increases with decreasing wavelength due to the increased Ge-based direct-band absorption. The value of 1.3 is reasonable among the values (0.8-1.7) reported in prior studies 24,25,26,60 and foundry PDK standards for high-speed optical interconnect applications 61 . Using this criterion, the operating coverage of a tensile Ge 0.99 Si 0.01 modulator (50-µm long, 0.7-µm wide) extends from ~1,580 to ~1,610 nm, where the IL is <6.8 dB.…”

“…One may exploit this wider window for future broadband PICs; however, this would give rise to new challenges for the development of existing photonic devices in PICs. For example, Ge, due to its CMOS-compatibility, considerable absorption coe cient 14 , and signi cant Franz-Keldysh effect 15 around 1,550 nm, has become an indispensable material in PICs for high-performance photodetectors 16,17,18,19,20 and electro-absorption (EA) modulators 21,22,23,24,25,26 . With years of development, Ge has shown an optimal adaptability to foundry processes.…”

CORNERSTONE’s Silicon Photonics Rapid Prototyping Platforms: Current Status and Future Outlook

“…This section provides some research highlights from the various SOI platforms that CORNERSTONE currently offers via its MPW service, including both passive [26,27] and active devices [28][29][30][31][32], and other components, which have been demonstrated by research groups around the globe. Since the optimal platform is dependent on the application, CORNERSTONE offers three different top Si overlayer thicknesses: 220 nm, 340 nm and 500 nm, with the 220 nm thickness targeting datacoms applications, the 340 nm thickness targeting low loss applications such as quantum photonics, and the 500 nm thickness targeting mid-IR (MIR) applications.…”

56 Gbps Si/GeSi integrated EAM

“…Here, we present an integrated rib waveguide modulator [30] realized on a selectively grown Si/GeSi cavity on 800 nm SOI wafer; the active area is a wrap-around PIN hetero-structure with dimension 1.5 µm x 40 µm, which enables electric field independency from the rib width and the possibility to tailor the waveguide dimension to provide better optical mode confinement and propagation for both polarizations. High speed measurements show a dynamic ER of 5.2 dB at a data rate of 56.2 Gbps, power consumption of 44 fJ/bit and modulation bandwidth of 56 GHz.…”