High power antiguided laser array fabricated usinga superlattice structure

Gray, J.; Marsh, J.H.; Roberts, J.S.

doi:10.1049/el:19941408

Cited by 2 publications

(1 citation statement)

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“…For SAStype arrays the interelement regions are built-in during the initial growth, and then etching and MOCVD regrowth occur in the element regions. A most recent approach, which does not involve regrowth, is the formation of low-index, high-gain regions via preferential Zn-diffusion disordering of a superlattice upper cladding layer [49].…”

Section: Arrays Of Antiguides and Resonant Leaky-wave Couplingmentioning

confidence: 99%

Phase-locked laser arrays revisited

Botez

Mawst

1996

IEEE Circuits Devices Mag.

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T phase-locked arrays of diode lasers was published in this magazine. Now, more than a decade later, major breakthroughs have occurred, both in theory and experiment, that have allowed phase-locked arrays to meet their promise of reliable, highcontinuous-wave (CW) power (= 0.5W) operation in diffraction-limited beams as well as multiwatt (5-10 W) near-diffraction-limited peak-pulsed-power operation. As an update to the 1986 article, this article describes a corrected picture for the array modes, arrays of antiguides and the concept of resonant leaky-wave coupling, and relevant recent results. OverviewBy comparison with other types of highpower, coherent semiconductor-based sources ("broad area"-type master oscillator power amplifier (MOPA), unstable resonator), phase-locked arrays have some unique advantages: graceful degradation; no need for optical isolators; no need for external optics to compensate for phasefront aberrations due to thermal-and/or carrier-induced variations in the dielectric constant; and, foremost, intrinsic beam stability with drive level due to a strong, built-in, real-index profile. The consequence is that, in the long run, phase-locked arrays are bound to be fundamentally more reliable than either MOPAs or unstable resonators.At the time the original review article [ 11 was written, three major types of phaselocked arrays had been investigated: evanescent-wave coupled, diffraction-coupled, and Y-junction coupled (see Fig. 5 in [l]).Up to 1988 the results were not at all encouraging: maximum diffraction-limited, singlelobe powers of = 50 mW or coherent powers (i.e., fraction of the emitted power contained within the theoretically defined diffractionlimited-beam pattern) never exceeding 100 mW. Thus, the very purpose of fabricating arrays (to surpass the reliable power level of single-element devices) was not achieved. The real problem was that researchers had taken for granted the fact that strong nearest-neighbor coupling implies strong overall coupling. In reality, as shown in Fig. 1, nearest-neighbor coupling is "series coupling," a scheme plagued by weak overall coherence and poor intermodal discrimination [2]. Strong overall interelement coupling occurs only when each element equally couples to all others (so-called "parallel coupling") [2]. In turn, intermodal discrimination is maximized and full coherence becomes a system characteristic. Furthermore, parallel-coupled systems have uniform near-field intensity profiles, and are thus immune to the onset of high-ordermode oscillation at high drive levels above threshold.Parallel coupling can be obtained in evanescent-wave-coupled devices, but only by weakening the optical-mode confinement, and thus making the devices vulnerable to thermal-and/or injected-carrier-induced variations in the dielectric constant. For both full coherence and stability it is necessary to achieve parallel coupling in structures of strong optical-mode confinement (i.e., builtin index steps 2 0.01). As shown below, only strongly guided, leaky-wave-coupled device...

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Section: Arrays Of Antiguides and Resonant Leaky-wave Couplingmentioning

confidence: 99%