We study theoretically the mechanisms of square-wave (SW) formation in vertical external-cavity Kerr-Gires-Tournois interferometers in the presence of anti-resonant injection. We provide simple analytical approximations for their plateau intensities and for the conditions of their emergence. We demonstrate that SWs may appear via a homoclinic snaking scenario, leading to the formation of complex-shaped multistable SW solutions. The resulting SWs can host localized structures and robust bound states.
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http://dx.doi.org/10.1364/OL.468236 | DOI Listing |
ACS Photonics
November 2024
Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States.
Harmonic and subharmonic RF injection locking is demonstrated in a terahertz (THz) quantum-cascade vertical-external-cavity surface-emitting laser (QC-VECSEL). By tuning the RF injection frequency around integer multiples and submultiples of the cavity round-trip frequency, different harmonic and subharmonic orders can be excited in the same device. Modulation-dependent behavior of the device has been studied with recorded lasing spectral broadening and locking bandwidths in each case.
View Article and Find Full Text PDFVertical-cavity surface-emitting laser (VCSEL) arrays that can emit orthogonally polarized light have shown broad application potential and market demand in the fields of optical communication, optical sensors, and biomedicine. Two kinds of polarization-switching VCSEL arrays based on anti-parallel (AP) oriented liquid crystal (LC) external cavities and twisted nematic (TN) oriented LC external cavities are proposed in this paper. The light is independently guided by the LC electrically, achieving uniform lasing of linearly polarized light with mutually orthogonal polarization modes and equal power.
View Article and Find Full Text PDFA vertical external cavity surface emitting laser (VECSEL) that uses intracavity second harmonic generation (SHG) and the twisted mode technique for power scaling was explored. The effects of the twisted mode technique are shown and discussed by examining the mode structure and spectrum of the fundamental mode. The maximum SHG output was 1 W at 458 nm while the fundamental was lasing in the TEM mode.
View Article and Find Full Text PDFReducing the repetition rate is one of the effective ways to increase the peak-power of the mode-locked pulses. However, for a vertical-external-cavity surface-emitting laser (VECSEL), the carrier lifetime in the nanosecond regime limits the further reduction of the pulse repetition rate, or in other words, limits the average output power of the mode-locked laser at low repetition rates, and ultimately restricts the peak-power of the pulses. This work uses a specially designed saturable Bragg reflector to start the mode-locking, and both low repetition rate and high average power are achieved simultaneously in a passively mode-locked VECSEL.
View Article and Find Full Text PDFACS Photonics
September 2024
Optoelectronics Research Centre (ORC), Physics Unit/Photonics, Faculty of Engineering and Natural Science, Tampere University, Korkeakoulunkatu 3, 33720 Tampere, Finland.
Membrane external-cavity surface-emitting lasers (MECSELs) represent a cutting-edge approach in pushing the performance boundaries of vertically emitting semiconductor lasers. The fundamental concept of employing an extremely thin gain membrane, spanning from hundreds of nanometers to a few micrometers in thickness and sandwiched between transparent heat spreaders, introduces novel opportunities through uniform double-sided optical pumping and enhanced heat dissipation from the active region. Additionally, these advantages of MECSELs facilitate more intricate band gap engineering possibilities for the active region by integrating multiple types of quantum wells (QWs) into a single laser gain structure.
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