Phase-locking of a 2.7-THz quantum cascade laser to a mode-locked erbium-doped fibre laser

Barbieri, Stefano; Gellie, P.; Santarelli, Giorgio; Ding, Lu; Maineult, W.; Sirtori, Carlo; Colombelli, R.; Beere, Harvey E.; Ritchie, D. A.

doi:10.1038/nphoton.2010.125

Cited by 166 publications

(96 citation statements)

References 43 publications

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“…With further improvement of the beam pattern, such a mixer together with recently developed THz quantum cascade lasers ͑QCL͒ as LO should allow the construction of new receivers 38,39 for detecting OI line at 4.7 THz for future airborne and space-borne telescopes. Much progress has been made on THz QCLs with regard to the operating frequency, temperature, output power, phase locking, [40][41][42] and heterodyne high-resolution spectroscopic measurement with a gas cell, 43 making them ready for applications.…”

Section: Discussionmentioning

confidence: 99%

Noise temperature and beam pattern of an NbN hot electron bolometer mixer at 5.25 THz

Zhang

Khosropanah

Gao

et al. 2010

Journal of Applied Physics

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We report the measured sensitivities of a superconducting NbN hot electron bolometer ͑HEB͒ heterodyne receiver at 5.25 THz. Terahertz ͑THz͒ radiation is quasioptically coupled to a HEB mixer with a lens and a spiral antenna. Using a measurement setup with black body calibration sources and a beam splitter in vacuo, and an antireflection coated Si lens, we obtained a double sideband ͑DSB͒ receiver noise temperature ͑T rec DSB ͒ of 1150 K, which is nine times h / 2k, where h is the Planck constant, the frequency, and k the Boltzmann constant. In addition, the measured far field beam patterns of the integrated lens antenna show nearly collimated beams from 2.5 to 5.3 THz that allow reliable measurement of T rec DSB using the vacuum setup. Our experimental results in combination with an antenna-to-bolometer coupling simulation suggest that the HEB mixer can work well at least up to 6 THz, making it suitable for next generation of high-resolution spectroscopic space telescopes and, in particular, for the detection of the neutral atomic oxygen line at 4.7 THz.

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Section: Discussionmentioning

confidence: 99%

Noise temperature and beam pattern of an NbN hot electron bolometer mixer at 5.25 THz

Zhang

Khosropanah

Gao

et al. 2010

Journal of Applied Physics

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“…It has already been verified that QCLs emitting in mid-infrared and terahertz wavelength ranges can be modulated and injection locked up to dozens of gigahertz [12][13][14][15] . The injection locking technique plays an important role in the phase locking [16,17] and broadband frequency comb operation [18,19] of terahertz QCLs.…”

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confidence: 99%

Beat note analysis and spectral modulation of terahertz quantum cascade lasers with radio frequency injection

Zhu

Wan

et al. 2017

Chin. Opt. Lett.

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We demonstrate the electrical beat note analysis and radio frequency (RF) injection locking of a continuous wave (cw) terahertz quantum cascade laser (QCL) emitting around 3 THz (∼100 μm). In free running the beat note frequency of the QCL shows a shift of ∼180 MHz with increasing drive current. The beat note, modulation response, injection pulling, and terahertz emission spectral characteristics in the different current regimes I, II, and III are investigated. The results show that in the current regime I close to the laser threshold we obtain a narrower beat note and flat response to the RF modulation at the cavity round trip frequency. The pulling effect and spectral modulation measurements verify that in the current regime I the RF injection locking is more efficient and a robust tool to modulate the mode number and mode frequency of terahertz QCLs.

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“…Terahertz (THz) frequency quantum cascade lasers (QCLs) have undergone rapid development in performance since their first demonstration, 1 finding potential application in a number of fields including astronomy, security screening, biomedicine, and cultural heritage, inter alia. 2,3 Operating across the 1.2-5 THz range, QCLs can provide high peak output powers (1 W), 4 a high spectral purity, 5,6 frequency, phase and amplitude stability, [7][8][9] and an ultrabroadband gain spanning an octave in frequency 10,11 at temperatures 199 K. 12 Most of the mentioned applications require sources with a low divergent spatial profile in the far-field as well as a fine spectral control of the emitted radiation. However, the double-metal waveguides conventionally employed to maximize the THz QCL operating temperature 12 suffer from a lack of efficient extraction and a poor collimation of the output radiation, 13 owing to the sub-wavelength dimensions of the resonant cavities.…”

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confidence: 99%

Distributed feedback terahertz frequency quantum cascade lasers with dual periodicity gratings

Castellano

Zanotto

et al. 2015

Applied Physics Letters

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We have developed terahertz frequency quantum cascade lasers that exploit a double-periodicity distributed feedback grating to control the emission frequency and the output beam direction independently. The spatial refractive index modulation of the gratings necessary to provide optical feedback at a fixed frequency, and simultaneously, a far-field emission pattern centered at controlled angles, was designed through use of an appropriate wavevector scattering model. Single mode terahertz (THz) emission at angles tuned by design between 0 and 50 was realized, leading to an original phase-matching approach for highly collimated THz quantum cascade lasers. Terahertz (THz) frequency quantum cascade lasers (QCLs) have undergone rapid development in performance since their first demonstration, 1 finding potential application in a number of fields including astronomy, security screening, biomedicine, and cultural heritage, inter alia. 2,3 Operating across the 1.2-5 THz range, QCLs can provide high peak output powers (1 W), 4 a high spectral purity, 5,6 frequency, phase and amplitude stability, 7-9 and an ultrabroadband gain spanning an octave in frequency 10,11 at temperatures 199 K. 12 Most of the mentioned applications require sources with a low divergent spatial profile in the far-field as well as a fine spectral control of the emitted radiation. However, the double-metal waveguides conventionally employed to maximize the THz QCL operating temperature 12 suffer from a lack of efficient extraction and a poor collimation of the output radiation, 13 owing to the sub-wavelength dimensions of the resonant cavities. Also, the strong longitudinal confinement provided by such microstrip waveguide configuration typically induces the laser to operate in a multimode regime.Distributed feedback (DFB) is commonly employed in semiconductor lasers to tailor the shape, symmetry, and frequency of the optical resonator eigenmodes, while simultaneously allowing stable single-mode operation. A DFB operates by introducing a periodic refractive index modulation along the propagation direction, which provides scattering between two guided states (feedback) or between a guided state and a radiative one (extraction), so that distributed optical feedback is achieved by coupling two counterpropagating modes through one of the spatial harmonics of a refractive index modulation. In fact, the latter is never purely sinusoidal and a grating with periodicity L contains spatial harmonics with wavevector k n ¼ n/L. Depending on whether the first, second, or third harmonic is used for feedback (n ¼ 1, 2, 3), the grating is described to be of the first, second or third order, respectively. 14 In the case of second 15,16 and third order 17 gratings, although a high spatial harmonic is used for optical feedback (k fb ¼ k 2 , k 3… ), the fundamental frequency is employed for radiation extraction (k e ¼ k 1 ). The ratio between the feedback wavevector k fb and the extraction wavevector k e determines the behavior of the laser: second order gratings emit...

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Phase-locking of a 2.7-THz quantum cascade laser to a mode-locked erbium-doped fibre laser

Cited by 166 publications

References 43 publications

Noise temperature and beam pattern of an NbN hot electron bolometer mixer at 5.25 THz

Noise temperature and beam pattern of an NbN hot electron bolometer mixer at 5.25 THz

Beat note analysis and spectral modulation of terahertz quantum cascade lasers with radio frequency injection

Distributed feedback terahertz frequency quantum cascade lasers with dual periodicity gratings

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