Toward practical application of fiber optical parametric amplifiers in optical communication systems.

摘要

One of the most powerful techniques in fiber optical communication systems is wave-length division multiplexing (WDM). By utilizing the large (∼300 nm), low-loss (0.2–0.4 dB/km) transmission bandwidth, a single fiber can transmit many wavelengths. One fiber can potentially support transmission of tens of terabits per second of information over thousands of kilometers, to meet the exponentially-growing capacity demand. One of the key components for WDM systems is the optical amplifier; currently the most widely used optical amplifier is the erbium-doped fiber amplifier (EDFA). However, its bandwidth and operating wavelength are limited. To mitigate the bandwidth limitation of EDFAs, alternative optical amplifiers have been investigated, and one of the most promising candidates is the fiber optical parametric amplifier (OPA).; Fiber OPAs are based on the third-order nonlinear susceptibility χ (3) in fiber. They can exhibit large bandwidth, and may find applications as optical amplifiers for WDM transmission. They also generate another wavelength, called idler, which contains the same modulation information as the input signal, with an inverted spectrum. This phase-conjugated idler can be used not only for wavelength conversion in WDM networks, but also for mid-span spectral inversion (MSSI) which can combat fiber dispersion, and even some of the detrimental fiber nonlinearities.; In this dissertation, a record high-performance fiber OPA with 60 dB signal gain, and a parametric wavelength converter with 40 dB of conversion gain and 3.8 dB of noise figure are experimentally demonstrated. An OPA with 92% pump depletion is analyzed theoretically and demonstrated experimentally. Polarization-independent OPA, both in one-pump and two-pump configurations are investigated. The differences between the two configurations are discussed and other solutions are also proposed to address some issues of linear orthogonal two-pump OPA. In addition, the applications of OPA: as a gain medium in OPO; as a second harmonic distortion (2HD) suppressor in CATV systems; as a novel device in wavelength exchange; and finally with the two-pump OPA technique, a method to lower idler broadening is proposed and implemented, and it shows an effective reduction of idler linewidth. They all show the versatile nature of OPA in various applications and promising steps in making practical OPA.