Optical mm-Wave Synthesizer Using Semiconductor Ring Laser (a Review)

Millimeter wave (mm-wave) technology is significant for military needs and applications due to its numerous advantages, such as huge bandwidth, deploying small antenna and high radar resolution. Due to atmospheric influence, mm-wave is important in short-range applications such as fire control radar. Similarly for the next-generation communication and military applications, high-speed radio over fiber networks are very crucial. In this paper, a review of the generation and modulation of millimeter-wave signal optically using semiconductor ring laser (SRL) has been done. The phenomena of optical injection locking and four-wave mixing are exploited in SRL to generate radio frequency (RF) optical signals. The signals with huge data rate can be transferred directly from an intensity modulated optical signal onto a RF optical signal with RF frequency tunable in steps of the free spectrum range (FSR) of SRL. They can be converted with flexible RF modulation formats over the optical carrier.