Polarization purity for active stabilization of diode laser injection lock

Injection locking of diode lasers is commonly used to amplify low power laser light but extremely sensitive perturbations in the current and temperature. To counter such perturbations, active stabilization often applied injection locked diode. We observe that laser’s polarization extinction ratio (PER) greatly increases when locked, therefore PER provides a measure lock quality. report robust based on PER, demonstrating technique at 399 nm wavelength where typically less stable than longer wavelengths. The feedback error signal compatible with standard proportional integral differential servo controllers, requires no additional optical components beyond isolator locking, enables large bandwidth.