3-CORE ARROW-TYPE DIODE-LASER - NOVEL HIGH-POWER, SINGLE-MODE DEVICE,AND EFFECTIVE MASTER OSCILLATOR FOR FLARED ANTIGUIDED MOPAS

A novel type of strong-index-guided laser structure for achieving cohe rent, high-power (similar to 1 W) reliable operation is proposed, anal yzed, and demonstrated for the first time, The three-core antiresonant -reflective-optical waveguide (ARROW) laser combines the relatively la rge fabrication tolerances of single-core ARROW-type devices with the excellent intermodal-discrimination properties of small-element-number (< 10) resonant antiguided arrays (i,e,, resonant optical-waveguide ( ROW) devices.) Thus, the three-core ARROW device should prove a more p ractical device to fabricate than large-element (> 10) ROW arrays, whi ch are known to have tight fabrication tolerances, For single-spatial- mode selectivity the device relies both on ARROW-type (lateral) reflec tors and interelement loss, The effect of interelement loss on the res onant in-phase mode and the unwanted nonresonant modes is calculated, and the results are used to design optimal structures, For structures of index step, Delta n, of 0.1; element/interelement width ratio of 5; 500 cm(-1) interelement-loss coefficient; and 7.5-mu m-wide individual elements, intermodal discrimination) 5 cm(-1) is obtained over a rela tively large range in an: similar to 0.01. Above-threshold analysis sh ows that, due to strong index guiding, the structures are virtually im mune to gain spatial hole burning, The central-lobe energy content is 65-70%, and the emitting aperture is 25 mu m, which should provide 1 W CW reliable single-mode power from devices with oxide-free facets, Pr eliminary experimental results are obtained from Al-free 0.98-mu m emi tting structures: diffraction-limited beam operation up to 30x thresho ld and 0.55 W peak pulsed output power, Finally it is shown that three -core ARROW devices used as integrated master oscillators (MO's) for f lared antiguided master-oscillator power amplifiers (MOPA's), provide uniform MOPA near-field intensity profiles, thus opening the way to ac hieving 3-5 W CW diffraction-limited power from stable, flared MOPA's.