Abstract: A method and apparatus are provided for stabilizing a distributed feedback semiconductor laser. The method includes the steps of comparing an optical output of a first oscillating mode of the semiconductor laser at a first polarization angle with an optical output of a second oscillating mode of the semiconductor laser at a second polarization angle orthogonal to the first polarization angle. A first feedback signal is provided to a cavity temperature controller of the semiconductor laser in response to detected differences of the compared first and second oscillating modes. The method further includes the step of comparing an output of the reference laser with an output of the semiconductor laser and providing a difference signal as a second feedback signal to the temperature controller of the semiconductor laser in response to detected differences between the reference laser and semiconductor laser.