High‐power RF photodiodes and their applications

Abstract

There has been an increasing interest in photonic generation of RF signals in the millimeter-wave (30 GHz ∼ 300 GHz) and/or terahertz-wave (0.1 THz ∼ 10 THz) regions, and photodiodes play a key role in it. This paper reviews recent progress in the high-power RF photodiodes such as UniTraveling-Carrier-Photodiodes (UTC-PDs), which operate at these frequencies. Several approaches to increasing both the bandwidth and output power of photodiodes are discussed, and promising applications to broadband wireless communications and spectroscopic sensing are described.Photodiode chip is bonded to the substrate with the antenna. This is a symbolic figure of RF photonics in this article. Antenna Photodiode Light RF signal

A Review on Terahertz Communications Research

“…The QCLs can operate at around 1 THz even though they require low-temperature and strong magnetic field [17]. Direct modulation of the QCLs is possible at modulation Attenuation between transmitter and receiver plotted over frequency and distance including freespace loss and atmospheric attenuation due to polar molecules frequencies of over 10 GHz [18] in addition to the use of external THz modulators such as 2DEG semiconductor modulators and metamaterial-based modulators. Figure 6 shows two electronics-based approaches together with representative components for THz receivers.…”

“…5 (b), the O/E converter is a key device. Figure 8 (a) and (b) show a high-output power photodiode called a uni-travelingcarrier photodiode (UTC-PD) [18] and a conventional pin photodiode, respectively. In the p-in-PD, the light absorption occurs in the intrinsic (depleted) InGaAs region, and electron-hole pairs are created.…”

Photonics for Millimeter-Wave and Terahertz Sensing and Measurement

“…The converted signals are finally radiated into free space by an antenna. As for O/E converters, we use a uni-traveling-carrierphotodiode (UTC-PD), which satisfies both wide bandwidth and high output power [10]. The J-band UTC-PD module has a 3-dB bandwidth of over 100 GHz, and a typical output power of over 100 μW at 300 GHz for a photocurrent of 10 mA [11].…”

Recent Progress and Future Prospect of Photonics-Enabled Terahertz Communications Research

“…For the modulation, an electro-optic intensity modulator (EOM) driven by electrical data signals from a pulse-pattern-generator is used to perform an amplitude-shift-keying (ASK) modulation up to 50 Gbit/s. The modulated optical signal is amplified by an Er-doped fiber amplifier (EDFA), and finally fed to the waveguide-mounted uni-travelling-carrier (UTC) photodiode [55].…”