Patent ID: 7468998

Claim:
A low-noise laser diode module comprising: a laser diode for emitting light with a wavelength in the range from ultra-violet to infrared; a driving circuit connected to said laser for providing drive current with RF modulation; and an automatic power control subsystem for adjusting drive current to maintain output power of said laser at a predetermined level; wherein: said driving circuit further comprising: a DC generator for generating DC bias tunable over a desired range and adjustable by the automatic power control subsystem; a local oscillator for generating RF signal of variable amplitude; a summing junction for superimposing said RF signal with said DC bias; a power supply control circuit for logically controlling order of supplying electrical power to said DC generator and to said local oscillator so that said laser diode will never be intolerably back biased; and a clamping diode for shunting reverse drive current or overpowered forward drive current for further protecting said laser diode from damage.