采用光子灯笼作为模式复用/解复用器,搭建了6×6的模分复用通信实验系统,利用6个模式作为独立传输信道,采用相位调制-相干检测的方式,通过离线信号处理,在10 km少模光纤的传输条件下实现了6×8.5 Gbit/s信号的良好传输。实验结果表明:当LP01、LP11a、LP11b、LP21a、LP21b、LP02模式的接收功率分别为-37.84 dBm、-36.47 dBm、-36.20 dBm、-35.27 dBm、-35.37 dBm、-35.79 dBm时,各路信号的误码率均可达到10 -3以下。

基于84km光传输链路, 对L波段光纤激光器进行了多速率接收及时钟数据恢复实验。采用伪随机序列非归零(NRZ)码、高性能LiNbO3电光晶体调制器, 调制速率从622Mb/s到2.7Gb/s。实验所用光纤激光器输出中心波长1610.28nm, 线宽0.1nm, 边模抑制比大于45dB, 输出功率稳定性优于0.02dB。对多速率接收眼图进行了测试, 其各速率信号眼图张开度好、眼皮厚度小, 结果表明测试系统无码间干扰和信号畸变, 信号的信噪比较高。在误码率为10-12时, 接收灵敏度可达到-30.62dBm, 过载光功率为-4.1dBm。分析了影响系统传输质量的因素, 研究了高速率下信号与时钟恢复后不同步的问题。

A novel gain-clamped long wavelength band (L-band) erbium-doped fiber amplifier (EDFA) is proposed and experimented by using a fiber Bragg grating (FBG) at the input end of the amplifier. This design provides a good gain clamping and decreases noise effectively. It uses two sections of erbium-doped fiber (EDF) pumped by a 1480-nm laser diode (LD) for higher efficiency and lower noise figure (NF). The gain is clamped at 23 dB with a variation of 0.5 dB from input signal power of -30 to -8 dBm for 1589 nm and NF below 5 dB is obtained. At the longer wavelength in L-band higher gain is also obtained and the gain is clamped at 16 dB for 1614 nm effectively. Because the FBG injects a portion of backward amplified spontaneous emission (ASE) back into the system, the gain enhances 5 dB with inputting small signal.

In this paper, a distributed Bragg reflection (DBR) type Er^(3+)/Yb^(3+) co-doped fiber laser of high output power and high slope efficiency was developed. Its gain medium was a 4.45-m-long Er^(3+)/Yb^(3+) co-doped fiber. When it was pumped by a 1064-nm Nd:YAG, the linewidth of output laser was measured as 0.072 nm by 3 dB and 0.192 nm by 25 dB at 1552.08 nm. The maximum output power was measured as 69 mW. Its power stability was < 5%, side mode suppression ratio was 59 dB, and the output wavelength stability was ±0.01 nm. The laser had a threshold of 12 mW and a slope efficiency of 22%.