The modules are roughly classified into four types of A, B, C, and D. The pins of the pumping laser are: positive and negative polarities (TEC+and TEC???) of a TEC (Peltier device), an anode (LD_A) and a cathode (LD_C) of driving of a laser diode, an anode (PA) and a cathode (PC) of a photo diode for monitoring, and thermistors (TR, TR) for temperature monitoring.