Tuning of the emission spectrum of a C3 laser

An investigation was made of tuning of the emission spectrum of a semiconductor C³ (cleaved-coupled-cavity) laser. The radiation power carried by a mode was found to be an oscillatory function of time and current in the modulating part of the laser: a change in the current by less than 1 mA resulted in a smooth variation of the mode power from its maximum value to the spontaneous noise level. The rate of change of the emission frequency with the current in the modulating part was different for different lasers and depended in a complex manner on the current.