High‐Speed Photodetectors on Silicon Photonics Platform for Optical Interconnect

Abstract

A photodetector (PD) converts optical signals into electrical ones and is widely used in optical interconnect. High-speed PDs are in high demand as they are necessary to meet requirements of large-capacity optical interconnect. Many high-performance PDs with various absorption materials and structures are demonstrated on silicon photonics platform, including germanium (Ge) PDs, germanium tin (GeSn) PDs, heterogeneous integrated III-V PDs, all silicon (Si) PDs, 2D material PDs, etc. These kinds of PDs continue to set new records of speed and open an era of ultrahigh-speed optical interconnect. A comprehensive summary of the state-of-the-art high-speed PDs on silicon photonics platform is necessary and meaningful. In this review, the basic metrics and key process technologies for the PDs are introduced, and various types of high-speed PDs based on silicon photonics platform are reviewed and discussed. Furthermore, the summary and perspectives are provided. It is hoped that this review can provide readers more insights into recent advances in high-speed PDs on silicon photonics platform and contribute to the further development.

High-Speed Carbon Nanotube Photodetectors for 2 μm Communications

“…We can estimate the response time from the commonly used optical time-bandwidth expression Δ f Δ t = 0.441 [Δ f is the 3 dB bandwidth, and Δ t is the full width at half-maximum (fwhm) pulse duration]. , For our CNT photodetector, the 3 dB bandwidth is over 40 GHz, indicating that the response time is less than 11 ps. Generally, the 3 dB bandwidth of a photodetector is mainly limited by the transit time and resistor–capacitor (RC) constant according to the following equations: f 3 d B = 1 / 1 / f T 2 + 1 / f R C 2 , where f T is the transit-time-limited bandwidth and f RC is the RC-limited bandwidth . The transit-time-limited bandwidth of the photodetector is approximately 675 GHz using the equation f T = 2 v / π l , where v is the carrier velocity (3 × 10 7 cm/s) and l is the carrier transit distance (200 nm).…”

“…Generally, the 3 dB bandwidth of a photodetector is mainly limited by the transit time and resistor–capacitor (RC) constant according to the following equations: f 3 d B = 1 / 1 / f T 2 + 1 / f R C 2 , where f T is the transit-time-limited bandwidth and f RC is the RC-limited bandwidth . The transit-time-limited bandwidth of the photodetector is approximately 675 GHz using the equation f T = 2 v / π l , where v is the carrier velocity (3 × 10 7 cm/s) and l is the carrier transit distance (200 nm). For a better understanding of the RC time constant with respect to bandwidth, the equivalent RC circuit model is shown in Figure S8.…”

“…Generally, the 3 dB bandwidth of a photodetector is mainly limited by the transit time and resistor–capacitor (RC) constant according to the following equations: , where f T is the transit-time-limited bandwidth and f RC is the RC-limited bandwidth . The transit-time-limited bandwidth of the photodetector is approximately 675 GHz using the equation , where v is the carrier velocity (3 × 10 7 cm/s) and l is the carrier transit distance (200 nm). For a better understanding of the RC time constant with respect to bandwidth, the equivalent RC circuit model is shown in Figure S8.…”

Multiband Signal Receiver by Using an Optical Bandpass Filter Integrated with a Photodetector on a Chip

“…To avoid being saturated, the PD should have a high-power processing capacity. By virtue of the rapid development of high-speed and high-power photodetectors on silicon photonics platforms, the high-frequency signals of the K-band, Ka-band and even broader bands can be received [ 30 , 31 , 32 , 33 , 34 , 35 ]. Last, but not least, the laser sources and phase modulators could be integrated with the OBPF and PD by advanced hybrid integration technology to realize the complete integration of MWP receiving systems [ 36 , 37 ].…”

Compact and Efficient Thin‐Film Lithium Niobate Modulators

“…In addition, by integrating the TFLN modulators with other optical components, such as optical amplifiers and wavelength division multiplexers, a more compact and efficient optical system can be realized on a single chip. [16][17][18][19] All of these make the TFLN modulator an attractive device.…”