Beam stability of buried-heterostructure quantum cascade lasers employing HVPE regrowth

Abstract

Measurements of beam stability for mid-infrared (IR)-emitting quantum cascade lasers (QCLs) are important for applications that require the beam to travel through air to remote targets, such as free-space communication links. We report beam-quality measurement results of narrow-ridge, 4.6 µm-emitting buried-heterostructure (BH) QCLs fabricated using ICP etching and HVPE regrowth. Beam-quality measurements under QCW operation exhibit M2 < 1.2 up to 1 W for ∼5 µm-wide ridges. 5 µm-wide devices display some small degree of centroid motion with increasing output power (< 0.125 mrad), which corresponds to a targeting error of ∼1.25 cm over a distance of 100 m.

Epitaxial Lateral Overgrowth of GaAsP for III‐V/Si‐Based Photovoltaics

“…The growth rate anisotropy inherent to HVPE does offer the possibility to planarize an uneven layer morphology during the growth itself; such planarization has been used during InP:Fe regrowth of quantum cascade laser structures. [ 22 ] Achieving such control over the relative growth rates would require extensive optimization of the GaAsP ELOG growth conditions, which is a possible topic for future studies.…”

“…The high selectivity, growth rate, and growth anisotropy inherent to HVPE makes it well suited for ELOG applications, [20] as well as other applications in orientation-patterned GaP growth and InP:Fe regrowth of buried heterostructure quantum cascade lasers. [21,22] The GaAsP material properties are studied by photoluminescence (PL) mapping and high-resolution X-ray diffraction (HRXRD). The spatial resolution in PL mapping enables studying the lateral growth and vertical growth separately, which reveals a higher P-incorporation during lateral growth while also demonstrating the beneficial impact of the ELOG technique.…”

Reverse-Taper Mid-Infrared Quantum Cascade Lasers for Coherent Power Scaling

“…Using an SiO 2 hardmask, selective regrowth of semiinsulating InP was performed using Hydride Vapor Phase Epitaxy (HVPE), similar to that reported previously [19]. While MOCVD is commonly used for selective regrowths, it is known to be dependent on processing conditions such as the regrowth thickness and the lateral undercut depth under the hard mask.…”

“…However, in some cases the pulsed slope-efficiency values of tapered devices can actually be higher than than those of straight devices. This may reflect that fact that there are absorption losses to the metal on both sides of ∼4.5 μm-wide buried ridges [19] and the degree of absorption may vary among devices, leading to higher internal losses and correspondingly lower slope efficiency.…”

Ultrafast Early Warning of Heart Attacks through Plasmon‐Enhanced Raman Spectroscopy using Collapsible Nanofingers and Machine Learning

“…Owing to the wide applications of emerging nanofabrication techniques, a high-aspect ratio nanofinger structure ensuring ultra-high SERS enhancement for sensitive molecular detection has been invented. [29][30][31][32][33][34][35][36][37][38] The nanofinger-a unique nanostructure created through nanoimprint lithography (NIL)achieves over 10 11 -fold SERS enhancement resulting from the precise engineering of the gap size. [39,40] The resultant gap plasmon structures realize chemical detection of single molecules which is currently difficult to achieve using other detection platforms.…”