A Current Controller for Tunable Near Infrared Diode Laser

A semiconductor diode laser current controller is described for room temperature operation. A current limiting circuit has been introduced in the controller to avoid the breakdown of the diode laser at high current. The diode current can be modulated for frequency modulation of the source and can be tuned over small wavelength ranges. Using the controller the absorption of the weak overtone band transitions of C2 H2 around 788 nm have been observed using the lock-in detection technique with a path length of only 1.5m.