Article

Gain competition in dual wavelength quantum cascade lasers

School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
Optics Express (Impact Factor: 3.53). 05/2010; 18(10):9900-8. DOI: 10.1364/OE.18.009900
Source: PubMed

ABSTRACT We investigated dual wavelength mid-infrared quantum cascade lasers based on heterogeneous cascades. We found that due to gain competition laser action tends to start in higher order lateral modes. The mid-infrared mode with the lower threshold current reduces population inversion for the second laser with the higher threshold current due to stimulated emission. We developed a rate equation model to quantitatively describe mode interactions due to mutual gain depletion. (C) 2010 Optical Society of America

1 Bookmark
 · 
130 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the past decade, tremendous development has been made in GaAs/AlGaAs based THz quantum cascade laser (QCLs), however, the maximum operating temperature is still limited below 200 K (without magnetic field). THz QCL based on difference frequency generation (DFG) represents a viable technology for room temperature operation. Recently, we have demonstrated room temperature THz emission (~ 4 THz) up to 8.5 μW with a power conversion efficiency of 10 μW/W2. A dual-period distributed feedback grating is used to filter the mid-infrared spectra in favor of an extremely narrow THz linewidth of 6.6 GHz.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2011; DOI:10.1117/12.899131 · 0.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate a dual wavelength mid-infrared Quantum Cascade Laser (QCL) utilizing a single active region to emit at 5-μm and 9-μm. The novelty lies in the large energy difference between the two lasing energies, achieved through simultaneous injection into the top 2 levels of a 4-level cascade employing InGaAs/InAlAs heterostructures latticematched to InP. The gain and losses at both wavelengths were measured by two different methods, Hakki-Paoli and cutback method, and were compared with theoretical predictions. The results for the gain of the 9-μm laser from the two techniques are consistently lower than theoretical predictions. Moreover, the mid-infrared losses are larger than expected at both wavelengths. We are investigating these devices for their potential application of quantum coherence to achieve lasing without inversion. The intense fields generated by the 9-μm laser are expected to partially eliminate the resonant absorption on the transition of interest at an energy corresponding to the difference between the energies of the two lasers. Our results on the dual wavelength QCL provide insights in the detail charge transport and optical properties of this design concept and open up the possibility for future optimization of inversionless lasers.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2012; DOI:10.1117/12.906048 · 0.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report mass-producible room-temperature electrically-pumped THz sources based on intra-cavity difference-frequency generation in mid-infrared InGaAs/AlInAs/InP quantum cascade lasers. Devices are grown by a commercial foundry using metal organic vapor phase epitaxy. A dual-stack active region possessing giant optical nonlinearity for 3.5 THz generation and a non-collinear Cherenkov waveguide THz outcoupling scheme is employed. Fabry–Pérot devices provided broad emission in the 3–4 THz range with a peak power of 5 $mu{rm W}$. Single color THz sources were processed using surface distributed feedback gratings to produce narrowband $({
    IEEE Photonics Technology Letters 02/2014; 26(4):391-394. DOI:10.1109/LPT.2013.2294941 · 2.18 Impact Factor

Full-text (2 Sources)

Download
12 Downloads
Available from
Sep 2, 2014