| Fiber amplifiers are the key devices in wavelength division multiplexing system of optical fiber communication, its performance directly impacts on the transmission bandwidth of system and the transmission distance of signal. Erbium-doped fiber amplifiers (EDFA) has many advantages, such as low noise, high gain, wide bandwidth, high pumping efficiency and stable performance, and EDFAs have become an important topic in the field of optical fiber communication, and has a very important role for improving the optical fiber communication capacity. At present, the C-band and L-band EDFA technology have been matured and commercialization. The S-band is adjacent to the common C-band, and the study of the S-band EDFA has great significance to expand communication bandwidth and improve the communication capacity.This paper take a more in-depth and detailed study on the design of the S-band EDFA, by the basis of the analysis of EDFA mechanism. We presents a novel structure of an S-band EDFA configuration and analyze its advantages and disadvantages. Finally, we propose a new type of fused tapered-fiber optic devices to improve the characters of this amplifier. The main work includes:1. A novel S-band EDFA configuration is proposed. This amplifier with two-stage double-pass configuration increases the utilization efficiency of the pump source, the amplifier gain and noise figure are improved compared with the other amplifier configurations.2. A novel temperature-controlled short-pass filter is proposed by using fiber fused tapered technology. The transmission mechanism of tapered fiber is analyzed through a combination way of theoretical analysis and experiment. Studies show, the cut-off wavelength of this filter can shift to longer with the temperature increased. The temperature coefficient of this filter is40nm/℃and the rejection efficiency of longer wavelength can be above35dB. This optical device is used to compensate for the EDFA flattened gain, and we obtain a gain-flattened S-band amplifier in1504-1524nm for the gain over20dB and the noise figure is less than5dB with the power of signal light is-30dBm. 3. Two kinds of Mach-Zehnder interferometers based on mode interference are proposed.The interferometers are not only used in the gain flattening filter of the amplifiers, can also beused to achieve high sensitivity temperature sensing, the sensitivity is much better than thefiber Bragg grating sensors. |
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