Richard K. DeFreez

Operating characteristics and elevated temperature lifetests of focused ion beam micromachined transverse junction stripe lasers

The operating characteristics of transverse junction stripe diode lasers with focused ion beam micromachined mirrors are shown to be comparable to those with cleaved facet mirrors. Stable cw operation for more than 2200 h was observed in an aging test at 55u2009°C.

Focused-Ion-Beam Micromachined Diode Laser Mirrors

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.

Focused-Ion-Beam Micromachining Of Diode Laser Mirrors

The development of a novel technique of forming optical quality surfaces in semiconductor materials is described. The technique exploits the precise sputter-etching afforded by a beam of 20 keV Ga+ ions focused to a 250 nm spot to micromachine features in the surfaces of semiconductor laser dice and wafers. Diode laser output mirrors of quality comparable to that of cleaved facets and two section coupled-cavity lasers which exhibit discrete and continuous tunability have been fabricated. Turning mirrors, angled at 45° to the epitaxial layers of the die to produce surface-emitting diode lasers, have also been micromachined with the focused ion beam (FIB). We have observed 330 mW of optical power from a surface-emitting 10 element phase-locked array. Development of FIB micromachining techniques needed to form the structures required for constructing a two-dimensionally coherent array of diode lasers are also described.

The effect of micromachining with focused ion beams on the life and power output of AlGaAs TJS lasers

Abstract Output mirrors of straight transverse junction stripe diode lasers have been micromachined with a focused ion beam and the performance shown to be comparable to those with cleaved facet mirrors. These devices have been operated stably in excess of 3500 hours at 55 C.