Buried laser waveguides in neodymium-doped BK-7 by K+–Na+ ion-exchange across a direct-bonded interface

We report a technique for producing single-step buried K+–Na+ ion-exchanged waveguide lasers in neodymium doped BK-7. Direct bonding is the basis for this process, providing atomic contact between two chemically modified BK-7-type substrates followed by a 350 °C treatment suitable for simultaneous annealing and intersubstrate ion exchange. Characterization of a 6 mm long device was performed using a Ti:sapphire laser operating at 808 nm. The resultant laser output exhibited TE polarized single-spatial-mode operation with losses of <0.4 dB cm−1 and a maximum output power of 8.5 mW for 249 mW of absorbed pump power.