Beam stability of buried-heterostructure quantum cascade lasers formed by ICP-etching and HVPE regrowthShow others and affiliations
2021 (English)In: Proceedings of SPIE - The International Society for Optical Engineering, SPIE-Intl Soc Optical Eng , 2021Conference paper, Published paper (Refereed)
Abstract [en]
Scaling the coherent power of mid-infrared (IR)-emitting quantum cascade lasers (QCLs) to the multi-watt range remains an important objective for applications where the laser beam needs to travel through air to remote targets, such as freespace communication links. For such applications requiring long-range pointing accuracy, measurements of beam stability are also important. We present beam-quality measurement results of narrow-ridge (4-5 μm), 4.6 μm-emitting buriedheterostructure (BH) QCLs. A 40-stage, step-tapered active-region (STA) structure was grown by MOCVD, and ICP etching was used to make deep ridges. InP:Fe was preferentially regrown in the field regions by using an SiO2 mask for ridge etching and Hydride Vapor Phase Epitaxy (HVPE). The HVPE process is attractive for selective regrowth, since high growth rates (0.2-0.3 μm/min) can be utilized, and highly planar top surfaces can readily be obtained. HVPE regrowth has been previously employed for BH devices of MBE-grown QCL ridges, but beam-stability measurements were not reported. HR-coated, 7.5 mm-long devices were measured under QCW operation (100 μsec pulse width, 0.5%-10% duty cycle) - very good beam quality factors, M2 < 1.2, were observed for both 4 μm and 5 μm ridge widths, but the narrower ridge exhibited better pointing stability. Collimated 5 μm-wide BH devices displayed some small degree of centroid motion with increasing power (< 0.125 mrad). This corresponds to a targeting error of ∼1.25 cm over a distance of 100 m. Significantly improved lateral-beam stability was observed for narrower ridge width, although at the expense of reduced output power.
Place, publisher, year, edition, pages
SPIE-Intl Soc Optical Eng , 2021.
Keywords [en]
Beam steering, HVPE, Quantum Cascade Laser, Semiconductor laser, Etching, III-V semiconductors, Indium phosphide, Laser beams, Quantum cascade lasers, Semiconducting indium phosphide, Silica, Beam quality measurement, Buried heterostructures, Free-space communication, Hydride vapor phase epitaxy, Pointing stability, Quantum cascade lasers (QCLs), Selective regrowth, Tapered active regions, Stability
National Category
Condensed Matter Physics Atom and Molecular Physics and Optics Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-309645DOI: 10.1117/12.2577342Scopus ID: 2-s2.0-85106693936OAI: oai:DiVA.org:kth-309645DiVA, id: diva2:1643223
Conference
Novel In-Plane Semiconductor Lasers XX 2021, 6 March 2021 through 11 March 2021
Note
Part of proceedings: ISBN 978-1-5106-4245-4
QC 20220309
2022-03-092022-03-092023-01-18Bibliographically approved