Sub-THz radio-over-fiber signal generation using external modulation

Abstract

This paper describes photonic technologies for millimeter-wave generation and distribution. External modulation would be useful for stable and high-quality radio-over-fiber signal generation, where frequency stability and spurious suppression are very important for radio services such as mobile communications, radio locations etc. This paper provides outline of radio-over-fiber signal generation techniques. Precise and high-speed lightwave optical modulation would play important roles for suppression of undesired spectrum components. Photonic harmonic generation would be useful for very high-frequency signals. Reciprocating optical modulators consisting of optical modulators and fiber Bragg gratings can provide optical modulation by sub-THz signals.

Self-Oscillating Optical Frequency Comb: Application to Low Phase Noise Millimeter Wave Generation and Radio-Over-Fiber Link

“…NE of the most useful attributes of microwave photonics technology is the availability of high bandwidth photodetection, which consequently enables the generation of microwave, mm-wave and THz signals through a variety of topologies and devices [1] [2]. This ranges from the use of discrete devices as in mode-locked lasers [3], gain-switched lasers [4], external modulation [5] [6], and nonlinear optics [7] to generate optical combs, through to more complex topologies such as optoelectronic oscillators (OEOs) [8] and recirculating optical loops [9]. In all cases the motivation is the feasibility of producing a signal directly in the optical domain, allowing it to be distributed and processed photonically.…”