The goal is to develop a tunable differential interferometer for wideband phase-to-amplitude conversion. The device must have high-optical power handling (> 300 mW) and low loss (
Benefit: High-performance RF/Analog fiber-optic links are used to remote sensitive RF signals from antenna to RF processors. A typical fiber-optic link utilizes a Mach-Zehnder amplitude modulator placed at remote antenna site. The amplitude modulator requires a DC bias electronics to set and maintain the proper linear operating at the remote site with varying temperature which is undesirable. An alternative amplitude modulation link architecture utilizes phase-to-amplitude conversion devices, such as a differential Mach-Zehnder interferometer (DMZI) to convert a phase-modulated link signal to an amplitude-modulated link signal directly prior to photo detection, thereby removing the need for any bias electronics at the RF encoding point. Although the phase modulation is broadband, the phase-to-amplitude conversion process results in links limited in bandwidth. The development of a low-loss tunable phase-to-amplitude conversion elements will allow the use of a bias-free phase modulated fiber-optic link covering wide RF frequency range.
Keywords: differential interferometer, differential interferometer, RF-over-fiber, Microwave Photonics, Phase Modulation, Fiber Optic, balanced link, RF/analog
