|
Focused-ion-beam micromachining is a new technique for forming optical quality surfaces in semiconductor laser materials. It exploits the precise, computer controlled, maskless, sputter-etching afforded by a beam of 15 - 25 keV Ga+ ions focused to a 50 to 250 nm spot to fabricate features in semiconductor laser dice and wafers. Diode laser output mirrors of quality comparable to that of cleaved facets have been fabricated. Focused-ion-beam micromachined (FIBM) single stripe coupled cavity lasers have demonstrated widely and continuously tunable single mode operation. As much as 80 mW of pulsed tunable single longitudinal mode optical power has been achieved with FIBM coupled cavity phase-locked arrays of AlGaAs semiconductor lasers. Hundreds of milliwatts of pulsed optical power has been observed from surface-emitting phase-locked arrays with FIBM turning and oscillator mirrors. The use of vector scanning of the ion beam to produce arbitrary surface contours, such as linear and curved turning mirrors and micron pitch gratings with various profiles, has been demonstrated. Recent results from elevated temperature aging tests suggest that FIBM does not cause significant damage to transverse junction stripe laser diodes and that it can be a promising tool for fabrication of etched mirrors for optoelectronic integrated circuits. Continuing research includes work on the fabrication of (i) monolithic dual micromachined coupled cavity single frequency lasers with wavelength separations continuously variable from 0 to 600 GHz, (ii) linear and parabolic turning mirrors for two-dimensionally coherent surface emitting arrays of lasers, (iii) total-internal-reflection mirrors to route light in the plane of the wafer, (iv) single wavelength micromachined coupled cavity lasers tunable at high frequencies, (v) a methanometer with a continuously tunable micromachined coupled cavity InGaAs/InP optical source, (vi) curved laser mirrors, and (vii) submicron, arbitrarily profiled, diffraction gratings for distributed feedback and dis-tributed Bragg reflector lasers.
|
