通過溫度控制優化光模塊性能

　　光網絡是寬帶互聯網業務發展的關鍵。光纖互連的大型交換機的數據傳輸每秒千兆比特，在光子控制的改善正在穩步增加，峰值帶寬。為了使光纖的可用帶寬最大化，制造商使用密集波分復用（DWDM），其中多個顏色的光同時通過光纖傳輸。對每個激光器發出的顏色的嚴格控制是至關重要的，因為通過保持更緊密的公差值，可以在給定長度的纖維中擠壓更多的通道。由于挖溝和鋪設電纜的費用通常超過購買更多的激光驅動器和放大器的成本，因此最大限度地提高光纖的吞吐量是關鍵。

　　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.