Patent ID: 7411992

Claim:
A light wavelength converting apparatus comprising: a semiconductor laser for emitting fundamental-wave light, said semiconductor laser including a gain region, a phase region, and a distributed Bragg reflection (DBR) region provided with a distributed Bragg reflector; a nonlinear optical device, said nonlinear optical device being adapted to receive the fundamental-wave light emitted by said semiconductor laser and to output second harmonic wave light of the fundamental-wave light; a first optical detector for monitoring an output of the fundamental-wave light; a second optical detector, said second optical detector being adapted to monitor the second harmonic wave light such that the second harmonic wave light can be controlled; and a control portion for controlling at least a drive current for driving said semiconductor laser, said control portion including a control parameter determiner and a wavelength controller, wherein said control parameter determiner is adapted to change a DBR current supplied to said DBR region and a phase current supplied to said phase region to obtain a changing point that corresponds to a discontinuous change in an electrical signal from said first optical detector, and to determine a control parameter for controlling the DBR current and the phase current such that the relationship between the DBR current and the phase current is not located on the changing point, wherein said-wavelength controller is adapted to control the DBR current and the phase current pursuant to the control parameter, such that an oscillation wavelength of said semiconductor laser can be continuously controlled, and wherein said control parameter determiner determines the control parameter for controlling the DBR current and the phase current such that the relationship between the DBR current and the phase current is approximately located on a line created by averaging a central line between two adjacent loci of the changing points appearing when the DBR current and the phase current are changed in a forward direction, and a central line between two adjacent loci of the changing points appearing when the DBR current and the phase current are changed in a backward direction, wherein said control parameter determiner determines proportional coefficients a and b, and a constant c in the following formula: a*I DBR 2 +b*I phase 2 =c where I DBR represents the DBR current and I phase represents the phase current.