FLAT-PHASEFRONT FANOUT-TYPE POWER-AMPLIFIER EMPLOYING RESONANT-OPTICAL-WAVE-GUIDE STRUCTURES

A novel type of fanout master-oscillator power amplifier (MOPA) device using resonant antiguided structures is proposed, modeled, and demons trated. Light injected in the central antiguide of an antiguided struc ture fans out, with increasing device length, due to resonant transmis sion between adjacent antiguide cores. After 1-mm device length the em itting aperture becomes almost-equal-to 100 mum wide, and the beam has a flat phasefront. The device has a strong built-in index step (DELTA n = 0.02-0.05), which makes it insensitive to the problems encountered with conventional fanout-type amplifiers: filamentation and drive-dep endent beam pattern. Experimental results include flat-phasefront and a diffraction-limited emission from a 130-mum-wide exit aperture when the entry aperture is a 3-mum-wide antiguide core.