Increasing the pump current range of a single-frequency laser diode tuned to the caesium D2 line

It is shown experimentally and theoretically that increasing the pump current of a laser diode and simultaneously lowering its temperature can ensure an order of magnitude increase in the range of pump currents where the diode emission frequency is tuned to the caesium D₂ line. The results are compared to the case where the laser diode and fibre Bragg grating temperatures are maintained constant and only the laser pump current is varied.