Mode-locking of a terahertz laser by direct phase synchronization

Maysonnave, Jean; Maussang, Kenneth; Freeman, Joshua R.; Jukam, Nathan; Madéo, Julien; Cavalié, P.; Rungsawang, Rakchanok; Khanna, Suraj P.; Linfield, E. H.; Davies, A. G.; Beere, Harvey E.; Ritchie, D. A.; Dhillon, Sukhdeep; Tignon, Jérôme

doi:10.1364/oe.20.020855

Cited by 25 publications

(14 citation statements)

References 31 publications

(38 reference statements)

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“…In fact, directly after the QCL is gain switched in the active mode locking regime, the pulse can be as short as 2.3 ps (9.6 ps) for the QCL with (without) GTI. This is a result of the broadband seed and the entire gain bandwidth being amplified in this transient range . Once in the steady state regime, a stable pulse train is observed.…”

Section: Resultsmentioning

confidence: 93%

Short Terahertz Pulse Generation from a Dispersion Compensated Modelocked Semiconductor Laser

Wang

Nong

Fobbe

et al. 2017

Laser & Photonics Reviews

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International audienceDispersion compensation is vital for the generation of ultrashort and single cycle pulses from modelocked lasers across the electromagnetic spectrum. It is typically based on addition of an extra dispersive element to the laser cavity that introduces a chromatic dispersion opposite to that of the gain medium. To date, however, no dispersion compensation schemes have been successfully applied to terahertz (THz) quantum cascade lasers for short and stable pulse generation in the THz range. In this work, a monolithic on-chip compensation scheme is realized for a modelocked QCL, permitting THz pulses to be considerably shortened from 16ps to 4ps. This is based on the realization of a small coupled cavity resonator that acts as an 'off resonance' Gires-Tournois interferometer (GTI), permitting large THz spectral bandwidths to be compensated. This novel application of a GTI opens up a direct and simple route to sub-picosecond and single cycle pulses in the THz range from a compact semiconductor source

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Section: Resultsmentioning

confidence: 93%

Short Terahertz Pulse Generation from a Dispersion Compensated Modelocked Semiconductor Laser

Wang

Nong

Fobbe

et al. 2017

Laser & Photonics Reviews

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“…Besides the technological interest of this measurement, it also provides a means to study laser emission in unprecedented detail and gain insight into the operation of QCLs. The type of signals observed from seeded QCLs can vary significantly from quasiconstant [4] to a single pulse per round trip [8] and multiple pulses per round trip [9]. This variety and complexity of signals hints at the dynamics of QCLs.…”

Section: Introductionmentioning

confidence: 99%

Laser-seeding dynamics with few-cycle pulses: Maxwell-Bloch finite-difference time-domain simulations of terahertz quantum cascade lasers

et al. 2013

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We implement a Maxwell-Bloch simulation for a two-level system within the finite-difference time-domain method to simulate the seeding of lasers by broadband pulse injection. The model does not make the slowly varying envelope approximation, and the full electromagnetic field is simulated so that we are able to obtain time-resolved seeding by few-cycle pulses. The model is compared to recent results on seeding of THz quantum cascade lasers to aid in the interpretation of their complex signals. The simulations are found to be in good agreement with the data when gain recovery times of 15 ps are used. Furthermore, we find that the emission from the laser depends only weakly on the seed used to initiate laser action. The model is readily applicable to any seeded laser system where few-cycle seed pulses are used.

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“…However, intra-cavity integration in the sub-wavelength (∼10–14 μm deep) cavities of available THz semiconductor lasers cannot be achieved without a significant increase of intra-cavity losses13. Although active mode-locking of THz QCLs has been achieved by exploiting injection seeding14, phase synchronization15, and by modulating the QCL driving current with an external RF synthesizer16, enabling the generation of laser pulses of a few ps duration14, passive mode-locking has not been achieved, due to the absence of suitable SAs in the THz region. As a further constraint, the inherently strong678 electron–phonon interaction in the QCL polar semiconductor gain medium leads to population inversion relaxation times as short as a few ps (refs 6, 14).…”

mentioning

confidence: 99%

Terahertz saturable absorbers from liquid phase exfoliation of graphite

et al. 2017

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Saturable absorbers (SA) operating at terahertz (THz) frequencies can open new frontiers in the development of passively mode-locked THz micro-sources. Here we report the fabrication of THz SAs by transfer coating and inkjet printing single and few-layer graphene films prepared by liquid phase exfoliation of graphite. Open-aperture z-scan measurements with a 3.5 THz quantum cascade laser show a transparency modulation ∼80%, almost one order of magnitude larger than that reported to date at THz frequencies. Fourier-transform infrared spectroscopy provides evidence of intraband-controlled absorption bleaching. These results pave the way to the integration of graphene-based SA with electrically pumped THz semiconductor micro-sources, with prospects for applications where excitation of specific transitions on short time scales is essential, such as time-of-flight tomography, coherent manipulation of quantum systems, time-resolved spectroscopy of gases, complex molecules and cold samples and ultra-high speed communications, providing unprecedented compactness and resolution.

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Mode-locking of a terahertz laser by direct phase synchronization

Cited by 25 publications

References 31 publications

Short Terahertz Pulse Generation from a Dispersion Compensated Modelocked Semiconductor Laser

Short Terahertz Pulse Generation from a Dispersion Compensated Modelocked Semiconductor Laser

Laser-seeding dynamics with few-cycle pulses: Maxwell-Bloch finite-difference time-domain simulations of terahertz quantum cascade lasers

Terahertz saturable absorbers from liquid phase exfoliation of graphite

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