通过温度控制优化光模块性能

　　通过温度控制优化光模块性能

　　光网络是宽带互联网业务发展的关键。光纤互连的大型交换机的数据传输每秒千兆比特，在光子控制的改善正在稳步增加，峰值带宽。为了使光纤的可用带宽最大化，制造商使用密集波分复用（DWDM），其中多个颜色的光同时通过光纤传输。对每个激光器发出的颜色的严格控制是至关重要的，因为通过保持更紧密的公差值，可以在给定长度的纤维中挤压更多的通道。由于挖沟和铺设电缆的费用通常超过购买更多的激光驱动器和放大器的成本，因此最大限度地提高光纤的吞吐量是关键。

　　The temperature of the laser diode is critical in maintaining a constant wavelength， so it must be controlled closely. This means controlling the temperature within ±0.1°C， while driving the laser diode with as much current as it can handle to provide a high enough output power to deliver data over long distances without external amplification.

　　However， the power requirements of the laser diode itself make this harder to achieve as the higher levels of energy required result in heat dissipation， which will tend to heat the laser diode. This， in turn， pushes the laser output color away from its target.

　　One way to address the self-heating problem is to mount a thermoelectric cooler （TEC） inside the laser-diode module. The TEC is a device that uses the Peltier effect. It typically comprises two kinds of materials and transfers heat from one side of the device to the other while a DC current is forced through it. The side from which heat is removed becomes cold. Contrastingly， the side to which heat is moved becomes hot. When the current reverses its direction， the previously cooler side heats up and the previously hotter side begins to cool. The cooling effect of the TEC is controlled by the amount of current that passes through it.