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Title: 8-beam local oscillator array at 47 THz generated by a phase grating and a quantum cascade laser

Authors:
; ; ; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1408782
Grant/Contract Number:
NA0003525
Resource Type:
Journal Article: Published Article
Journal Name:
Optics Express
Additional Journal Information:
Journal Volume: 25; Journal Issue: 24; Related Information: CHORUS Timestamp: 2017-11-13 21:29:56; Journal ID: ISSN 1094-4087
Publisher:
Optical Society of America (OSA)
Country of Publication:
United States
Language:
English

Citation Formats

Mirzaei, B., Silva, J. R. G., Hayton, D., Groppi, C., Kao, T. Y., Hu, Q., Reno, J. L., and Gao, J. R. 8-beam local oscillator array at 47 THz generated by a phase grating and a quantum cascade laser. United States: N. p., 2017. Web. doi:10.1364/OE.25.029587.
Mirzaei, B., Silva, J. R. G., Hayton, D., Groppi, C., Kao, T. Y., Hu, Q., Reno, J. L., & Gao, J. R. 8-beam local oscillator array at 47 THz generated by a phase grating and a quantum cascade laser. United States. doi:10.1364/OE.25.029587.
Mirzaei, B., Silva, J. R. G., Hayton, D., Groppi, C., Kao, T. Y., Hu, Q., Reno, J. L., and Gao, J. R. 2017. "8-beam local oscillator array at 47 THz generated by a phase grating and a quantum cascade laser". United States. doi:10.1364/OE.25.029587.
@article{osti_1408782,
title = {8-beam local oscillator array at 47 THz generated by a phase grating and a quantum cascade laser},
author = {Mirzaei, B. and Silva, J. R. G. and Hayton, D. and Groppi, C. and Kao, T. Y. and Hu, Q. and Reno, J. L. and Gao, J. R.},
abstractNote = {},
doi = {10.1364/OE.25.029587},
journal = {Optics Express},
number = 24,
volume = 25,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1364/OE.25.029587

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  • We present an 8-beam local oscillator (LO) for the astronomically significant [OI] line at 4.7 THz. The beams are generated using a quantum cascade laser (QCL) in combination with a Fourier phase grating. The grating is fully characterized using a third order distributed feedback (DFB) QCL with a single mode emission at 4.7 THz as the input. The measured diffraction efficiency of 74.3% is in an excellent agreement with the calculated result of 75.4% using a 3D simulation. We show that the power distribution among the diffracted beams is uniform enough for pumping an array receiver. To validate the gratingmore » bandwidth, we apply a far-infrared (FIR) gas laser emission at 5.3 THz as the input and find a very similar performance in terms of efficiency, power distribution, and spatial configuration of the diffracted beams. Both results represent the highest operating frequencies of THz phase gratings reported in the literature. By injecting one of the eight diffracted 4.7 THz beams into a superconducting hot electron bolometer (HEB) mixer, we find that the coupled power, taking the optical loss into account, is in consistency with the QCL power value.« less
  • Abstract not provided.
  • A phase-locked quantum cascade laser (QCL) array consisting of one hundred elements that were integrated in parallel was achieved at λ ∼ 4.6 μm. The proposed Fraunhofer’s multiple slits diffraction model predicted and explained the far-field pattern of the phase-locked laser array. A single-lobed far-field pattern, attributed to the emission of an in-phase-like supermode, is obtained near the threshold (I{sub th}). Even at 1.5 I{sub th}, greater than 73.3% of the laser output power is concentrated in a low-divergence beam with an optical power of up to 40 W.
  • Grating-coupled surface-emitting (GCSE) lasers generally operate with a double-lobed far-field beam pattern along the cavity-length direction, which is a result of lasing being favored in the antisymmetric grating mode. We experimentally demonstrate a GCSE quantum-cascade laser design allowing high-power, nearly single-lobed surface emission parallel to the longitudinal cavity. A 2nd-order Au-semiconductor distributed-feedback (DFB)/distributed-Bragg-reflector (DBR) grating is used for feedback and out-coupling. The DFB and DBR grating regions are 2.55 mm- and 1.28 mm-long, respectively, for a total grating length of 5.1 mm. The lasers are designed to operate in a symmetric (longitudinal) grating mode by causing resonant coupling of the guided optical modemore » to the antisymmetric surface-plasmon modes of the 2nd-order metal/semiconductor grating. Then, the antisymmetric modes are strongly absorbed by the metal in the grating, causing the symmetric mode to be favored to lase, which, in turn, produces a single-lobed beam over a range of grating duty-cycle values of 36%–41%. Simulations indicate that the symmetric mode is always favored to lase, independent of the random phase of reflections from the device's cleaved ends. Peak pulsed output powers of ∼0.4 W were measured with nearly single-lobe beam-pattern (in the longitudinal direction), single-spatial-mode operation near 4.75 μm wavelength. Far-field measurements confirm a diffraction-limited beam pattern, in agreement with simulations, for a source-to-detector separation of 2 m.« less
  • A novel phase-type quantum-dot-array diffraction grating (QDADG) is reported. In contrast to an earlier amplitude-type QDADG [C. Wang et al., Rev. Sci. Instrum. 78, 053503 (2007)], the new phase-type QDADG would remove the zeroth order diffraction at some certain wavelength, as well as suppressing the higher-order diffractions. In this paper, the basic concept, the fabrication, the calibration techniques, and the calibration results are presented. Such a grating can be applied in the research fields of beam splitting, laser probe diagnostics, and so on.