  We report on a device to electronically stabilize the optical injection lock
of a semiconductor diode laser. Our technique uses as discriminator the peak
height of the laser's transmission signal on a scanning Fabry-Perot cavity and
feeds back to the diode current, thereby maintaining maximum optical power in
the injected mode. A two-component feedback algorithm provides constant
optimization of the injection lock, keeping it robust to slow thermal drifts
and allowing fast recovery from sudden failures such as temporary occlusion of
the injection beam. We demonstrate the successful performance of our
stabilization method in a diode laser setup at 399 nm used for laser cooling of
Yb atoms. The device eases the requirements on passive stabilization and can
benefit any diode laser injection lock application, particularly those where
several such locks are employed.
