A simple scheme for the efficient frequency doubling of a Fabry-Perot diode
laser in a bow tie ring cavity is described. By feeding back the ring cavi
ty transmission into the laser after reflection off a grating, the diode la
ser operates in single mode and the frequency locks to the cavity resonance
. Using a simple analytic form of the beam parameters for the ring cavity,
the optimum cavity configuration is found for a high degree of mode matchin
g between the diode output beam and the ring cavity. (C) 2000 American Inst
itute of Physics. [S0003-6951(00)03308-8].