Optical Transceiver Module plays the role of photoelectric conversion in optical communication network. It is composed of opto-electronic devices, functional circuits and optical interfaces. The most important parts of optical transceiver modules are Laser Emitting and Laser Receiving devices. The Laser Emitting part of optical transceivers is called TOSA (Transmit Optical Sub-Assembly), its key device is Laser Diode; the Laser Receiving part is called ROSA (Receiver Optical Sub-Assembly), the key device is Photo Diode. Optical Transceivers are BOSA (Bi-directional Optical Sub-Assembly) Assemblies and packaged with Laser Diode and Photo Diode together. TOSA (Transmit Optical Sub-Assembly) and ROSA (Receiver Optical Sub-Assembly) are essential components in the uni-directional transceivers. Laser Diodes(LD), the key emitting devices of optical transceivers, have FP, DFB, VCSEL, EML types, etc. Generally, the laser diode (LD Chip), backlight detection tube (PIN PD Chip), thermistor, TEC cooler and optics are integrated in the package. Components include collimation mechanism and more.