Optimized Second-Harmonic Generation in Quantum Cascade Lasers

Claire F. Gmachl, Alexey Belyanin, Deborah L. Sivco, Milton L. Peabody, Nina Owschimikow, A. Michael Sergent, Federico Capasso, Alfred Y. Cho

Research output: Contribution to journalArticlepeer-review

116 Scopus citations


Optimized second-harmonic generation (SHG) in quantum cascade (QC) lasers with specially designed active regions is reported. Nonlinear optical cascades of resonantly coupled intersubband transitions with giant second-order nonlinearities were integrated with each QC-laser active region. QC lasers with three-coupled quantum-well (QW) active regions showed up to 2 μW of SHG light at 3.75 μm wavelength at a fundamental peak power and wavelength of 1 W and 7.5 μm, respectively. These lasers resulted in an external linear-to-nonlinear conversion efficiency of up to 1 μW/W2. An improved 2-QW active region design at fundamental and SHG wavelengths of 9.1 and 4.55 μm, respectively, resulted in a 100-fold improved external linear-to-nonlinear power conversion efficiency, i.e. up to 100 μW/W 2. Full theoretical treatment of nonlinear light generation in QC lasers is given, and excellent agreement with the experimental results is obtained. For the best structure, a second-order nonlinear susceptibility of 4. 7 × 10-5 esu (2 × 104 pm/V) is calculated, about two orders of magnitude above conventional nonlinear optical materials and bulk III-V semiconductors.

Original languageEnglish (US)
Pages (from-to)1345-1355
Number of pages11
JournalIEEE Journal of Quantum Electronics
Issue number11
StatePublished - Nov 2003

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


  • Intersubband transitions
  • Mid-infrared
  • Multiple-wavelength emission
  • Nonlinear optics
  • Quantum cascade laser
  • Quantum wells
  • Second-harmonic generation


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