Investigation of wavelength conversion by four-wave mixing in semiconductor optical amplifiers

Citation

Geraghty, David Francis (1997) Investigation of wavelength conversion by four-wave mixing in semiconductor optical amplifiers. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/rqrk-zs39. https://resolver.caltech.edu/CaltechETD:etd-01092008-081143

Abstract

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Four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) is investigated for wavelength conversion in high-speed, all-optical networks. The design of the wavelength converter is optimized and the system performance limitations imposed by the fundamental physical principles involved in the SOA FWM process are characterized.

Single channel conversion performance is evaluated. The FWM efficiency ultimately determines many systems-level characteristics of the wavelength converter. The spectral range of our wavelength converter is characterized. Wide wavelength conversions of up to 18 nm and complete coverage of a 10 nm spectral range are demonstrated, while maintaining a BER performance of better than [...] at 10 Gb/s. The converter also demonstrates a large dynamic input range of over 10 dB at 2.5 Gb/s. And the first characterization of cascaded FWM SOA wavelength converters, cascading conversion of up to 10 nm at 10 Gb/s, is performed.

With a simple modification of the converter design to a dual-pump configuration, the wavelength converter is able to provide nearly polarization insensitive performance. The converted signal's magnitude varies by less than 1.5 dB and its sensitivity varies by less than 2 dB for 2.5 Gb/s signals over the entire range of input polarizations.

Time resolved spectral analysis is performed to evaluate the spectral properties of the wavelength converter. A pattern-dependent additional chirp is measured on the signal, primarily resulting from fluctuations in the gain saturation of the SOA. This degradation to the optical phase conjugation, intrinsic to the SOA FWM process, is minimal enough to allow dispersion compensation by mid-span spectral inversion. Error-free detection of a directly modulated 10 Gb/s signal is achieved over 120 km.

Additional demonstrations are also presented. Multi-channel wavelength conversion and dynamic routing are successfully performed. Finally, some work on a microcavity erbium-doped fiber laser, initially designed and developed for use as a tunable source for wavelength-division multiplexed networks, is presented.

Thesis Files