Patent ID: 8306076

Claim:
A driver circuit for a wavelength tunable laser diode that includes an optically gain regions to generate light supplied with a first current from a first source through a first electrode, a wavelength selective region to set a wavelength of said light supplied with a second current from a second source through said second electrode, and an optical amplifying region to amplify said light supplied with a third current from a third source through a third electrode, said driver circuit comprising: a DC/DC converter configured to couple with at least two of said first to third sources; and a voltage controller for controlling an output of said DC/DC converter provided to said at least two of said first to third sources, wherein said voltage controller, by monitoring said outputs of said at least two of said first to third sources individually, sets said output of said DC/DC converter equal to a voltage greater than a largest output among said outputs by a preset margin to operate said sources normally.