Research On Optical Amplification Technology In The Large Scale Fiber-Optic Hydrophone Array

Optical amplification is one of the key technologies in large scale fiber-optic hydrophone array. Er3+-doped fiber amplifier (EDFA) is an excellent solution. Compared with EDFA in communication nets, EDFA in sensor array demands more on gain and noise figure. For this special application, this dissertation has done some foundational researches as follows:1. Theoretical model of EDFA is established based on the classical Giles model and most of the parameters in this model are replaced by commodity parameters. Numerical method is used to establish an operational system which can do most simulation of EDFA.2. The amplified spontaneous emission (ASE) is studied. Both the forward and backward ASE is simulated and their characters are analyzed in detail. Then the dual stage cascade structure is presented as a solution to reduce the ASE noise. Simulation and experimental results are presented to show the reduction efficiency.3. Upconversion in the EDFA is analyzed. The green fluorescence is approved to be a kind of upconversion. Its mechanism and characters is studied theoretically and experimentally. The cluster parameter k is presented to reduce upconversion, and the smaller the k, the lower the upconversion. Another method to reduce upconversion is to dope Al and P together, which can make the ESA spectra shifted toward short wavelength.4. Pulse signal is researched when amplified by EDFA. For signal with a frequency of 10 kHz, the gain is about 3dB higher than sequence signal amplification, but in time domain, aberrance occurred with the amplified signal. Simulations of gain and aberrance are done to study the amplification of pulse signal with a frequency of 0.25MHZ.This dissertation is part of the basic studies on large scale fiber-optic hydrophone array. The researches in this dissertation provide a foundation for EDFA development in our institute.