Broadband Frequency-Modulated Continuous-Wave Signal Generation by Optical Modulation Technique

Abstract

Optical frequency-modulated continuous-wave (FM-CW) signal generation with a bandwidth of 35 GHz and a pulse duration of 1 μs in the range of 75-110 GHz is demonstrated with an optical frequency multiplier consisting of an optical modulator and optical filters. The FM-CW signal generator is used as a signal source for the surveillance of obstacles and debris in a large area by a distributed radar system connected to the optical fiber network. The system for millimeter-wave FM-CW signal generation is realized using the functions of a multi-frequency band and segmentation of the radar heads with several channels to avoid radio-frequency interference. The wavelength-division multiplexing technology with simple optical heterodyning aids in realizing these functions with high availability. IndexTerms-Frequency-modulated continuous-wave, millimeter-wave radar, optical frequency domain reflectometry, optical modulation, radio over fiber.

Dual-Chirp Microwave Waveform Generation Using a Dual-Parallel Mach-Zehnder Modulator

“…Compared with a single-chirp microwave waveform, the range-Doppler resolution was significantly increased. Since the dual-chip microwave waveform was generated in the optical domain, the technique can be used in a distributed radar system in which microwave waveforms are distributed over optical fibers to take advantage of the ultra-broad bandwidth and low loss of modern photonics technology [14,15].…”

Optical-network-connected multi-channel 96-GHz-band distributed radar system

“…A bandpass filter (BPF) and a power amplifier (PA) chain optimize the signal power launched into an optical two-tone generator based on an optical modulation technology with unwanted harmonic suppression. [13][14][15] For λ 2 , AWG2 with a frequency doubler (x2) generates the frequency chirp signal with a bandwidth of 1 GHz at a center frequency of 24.5 GHz, whose pulse duration is the same as for the signal of λ 1 . The optical two-tone generators work as a frequency quadrupler; a 24-GHz signal input generates an optical two-tone signal with a frequency separation of 96 GHz.…”

“…1). 13 Nowadays, the optical modulation technology can provide precise optical signal generation with an extinction ratio greater than 40 dB, which is comparable to the radio technology, even in the MMW band. Thus, a combination of a precise synthesizer with several low-cost MMW radar heads, which are composed of only a radio frontend, can expand the coverage while maintaining high ranging resolution.…”

W-band active imaging by photonics-based synthesizer

“…In this sense, a centralized seed-signal generator by photonics with a large number of remote transmitters with the PM can easily generate and distribute the synchronized signals over a low-transmission-loss optical fiber network to the optical to millimeter-wave converters. 4 High functional imaging will be realized by the photonics-based signal generation and distribution technologies.…”