High-speed waveguide Ge/Si avalanche photodiode with a gain-bandwidth product of 615  GHz

Abstract

High-sensitivity and high-bandwidth receivers are always demanded for high-speed optical link systems. As a key element, an avalanche photodiode (APD) is often regarded as one of the most attractive options for achieving high sensitivity owing to the potential high internal gain. In this paper, a 48-GHz waveguide Ge/Si avalanche photodiode operating at the O-band (1310 nm) is designed with a lateral reach-through structure and fabricated with simplified processes. The fabricated APD shows a high primary responsivity of 0.93 A/W at the unit-gain voltage of − 4.7 V . It has an avalanche gain of 12.8 and a record gain-bandwidth product of ∼ 615 GHz with an input optical power of − 15 dBm when operating at a bias voltage of − 14 V . The present Ge/Si APD is used successfully for high-speed data receiving, showing a sensitivity improvement about 7.6 dB for KP4-FEC operation (i.e., BER = 2.4 × 10 − 4 ) with 50 Gbps non-return-to-zero (NRZ) data, compared with the case of using the reference PIN PD on the same chip. The sensitivity of the receiver with the present APD for NRZ signals is about − 21.3 dBm , − 17.8 dBm , and − 12.6 dBm for KP4-FEC operation with different data rates of 50 Gbps, 80 Gbps, and 100 Gbps, while the sensitivity for four-level pulse amplitude modulation signals is about − 13.2 dBm and − 11.3 dBm for KP4-FEC operation with different data rates of 25 and 50 Gbaud. Such high-performance APDs pave the way to achieve high-speed and high-sensitivity data transmissions.

High-Power Ge/Si Waveguide Photodetector

“…Among them, high-power photodetectors are extremely important as an indispensable component for photoelectric conversion. Even though III–V and silicon material platforms are available for various passive and active photonic devices for microwave photonics, , silicon photonics is recognized with great potential due to its unique advantages of complementary metal-oxide-semiconductor (CMOS) compatibility, which enables low-cost and massive production. − For silicon photonics, germanium is a superior alternative for light detection due to the mature process of direct epitaxy on silicon, and consequently, there have been a lot of impressive works reported for Ge/Si photodetectors in the past decade. , …”

“…4−8 For silicon photonics, germanium is a superior alternative for light detection due to the mature process of direct epitaxy on silicon, and consequently, there have been a lot of impressive works reported for Ge/Si photodetectors in the past decade. 9,10 In recent years, several structures have been proposed to improve the high-power photodetection performance. 11−23 Among them, a traditional method for high-power detection is using the traveling-wave electrode loaded with photodetector (TWPD) array at the sacrifice of large footprints.…”

High-Bandwidth Zero-Biased Waveguide-Integrated p-n Homojunction Graphene Photodetectors on Silicon for a Wavelength Band of 1.55 μm and Beyond

“…Recently, the mid-infrared (MIR) silicon photonics attracts more and more attention due to the applications of lab-on-chip for sensing and next-generation optical communications at 2 μm. , However, it remains a challenge to realize monolithically integrated silicon photodetectors beyond 1.55 μm by using conventional bulk materials. For example, Ge has a cutoff wavelength of ∼1.6 μm for efficient absorption, and III–V/II–VI materials − have a large lattice mismatch with silicon. Fortunately, two-dimensional materials (2DMs) provide a promising solution because of excellent optoelectronic properties, broadband optical absorption ability, and CMOS compatibility potential .…”

High‐Performance Silicon Photonic Filter Using Subwavelength‐Structure Multimode Waveguide Gratings

“…Silicon photonics has been widely employed for various applications because of its unique advantages, including the DOI: 10.1002/lpor.202300485 compatibility with the complementary metal-oxide-semiconductor (CMOS) manufacturing process, high integration density, low waveguide losses, as well as the potential cost-effectiveness. [1][2][3] For optical interconnects and optical sensing, a variety of ultra-compact silicon photonic devices have been successfully developed, including active components [4][5][6] (such as lasers, modulators, and photodetectors) and passive components (such as photonic filters, [7] waveguide crossings, [8] polarization-handling devices, [9,10] and mode-manipulation devices [11] ). One of the most important components among them is a silicon photonic filter, which is frequently used for both spectroscopic sensing and wavelength-division multiplexing (WDM) optical communications.…”