{
  "id": "1601.03212",
  "version": "v1",
  "published": "2016-01-13T12:03:22.000Z",
  "updated": "2016-01-13T12:03:22.000Z",
  "title": "Low-threshold RNGH instabilities in quantum cascade lasers",
  "authors": [
    "Nikola Vukovic",
    "Jelena Radovanovic",
    "Vitomir Milanovic",
    "Dmitri L. Boiko"
  ],
  "categories": [
    "cond-mat.mes-hall",
    "physics.optics"
  ],
  "abstract": "A theoretical study on low-threshold multimode instabilities in quantum cascade lasers (QCLs) and laser diodes (LDs) is presented. Previously, low threshold Risken-Nummedal-Graham-Haken (RNGH) instabilities were reported in several experimental studies of QCLs. They were attributed so far to the combined effect of the induced grating of carrier population and of a built-in saturable absorption feature that may be present in the monolithic single-section cavity of these Fabry-P\\'erot lasers. Here we show that low-threshold RNGH instabilities in QCLs occur due to a carrier coherence grating induced in the gain medium and not due to intracavity saturable absorption. We find that QCLs with a few mm long cavity exhibit intermittent RNGH self-pulsations while regular self-pulsations are possible in short-cavity QCLs, with the cavity length of 100 um or smaller. We examine a transient behavior to RNGH self-pulsations in short-cavity QCLs and find features that resemble cooperative superradiance. Our findings open a practical way of achieving ultra-short pulse production regimes in the mid-infrared spectral range. Applying same approach to semiconductor laser diodes (LDs) we explain the absence of RNGH self-pulsation in LDs based on a quantum well gain media, while practically established method for reaching the ultrafast coherent emission regimes in LDs is to incorporate a separately contacted saturable absorber section in the LD cavity.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-01-13T12:03:22.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "quantum cascade lasers",
      "low-threshold rngh instabilities",
      "ultra-short pulse production regimes",
      "contacted saturable absorber section",
      "rngh self-pulsation"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2016arXiv160103212V"
    }
  }
}