Patent ID: 8073030
Filing Date: 2011-12-06
Classification: H01S

Abstract:
1. A laser driver circuit for driving a semiconductor laser diode, comprising: a current source to provide a bias current to said laser diode; a switching transistor connected in parallel to said semiconductor laser diode, said switching transistor shunting said bias current provided from said current source; a bias generator to provide a bias to said switching transistor; an auto power control circuit for setting an average power and an extinction ratio of light output from said laser diode in constant independent of temperatures; and a pre-amplifier for outputting a driving signal to said switching transistor, wherein said bias is varied as a temperature of said laser diode varies, wherein said auto power control circuit outputs a first control signal and a second control signal, said first control signal being provided to said pre-amplifier to vary an amplitude of said driving signal, said second control signal being provided to said current source to vary said bias current supplied to said laser diode, wherein said driving signal superposed with said bias is provided to said switching transistor.