Sub-picosecond all-optical gate utilizing aN intersubband transition

Abstract

All-optical gate-switch operation utilizing GaN intersubband-transition has been achieved by reducing edge dislocation density in the epitaxial layers. The diminution of dislocation was accomplished by MBE regrowth on an MOCVD-grown layer. Excess propagation loss for transverse magnetic polarization decreased due to the reduction of the dislocation. By the improvement of the propagation property, sub-picosecond all-optical gate with an extinction ratio of more than 10 dB was accomplished with an input pulse energy of 150 pJ. Moreover, the insertion loss with the switch on was improved.