Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes

Nong, Hanond; Pal, Shovon; Markmann, Sergej; Hekmat, Negar; Mohandas, Reshma A.; Dean, Paul; Li, Lianhe; Linfield, E. H.; Davies, A. G.; Wieck, A. D.; Jukam, Nathan

doi:10.1063/1.4896032

Cited by 9 publications

(5 citation statements)

References 30 publications

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“…1(a)). The electric field of the THz pulses transmitted through the opposite facet is then measured via free space electro-optic sampling [27,28]. Immediately after the arrival of the first THz pulse (the seed), the gain of the QCL is driven above its threshold with an RF bias pulse.…”

Section: Measurement Set-upmentioning

confidence: 99%

Two-dimensional coherent spectroscopy of a THz quantum cascade laser: observation of multiple harmonics

Markmann¹,

Nong²,

Pal³

et al. 2017

Opt. Express

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Two-dimensional spectroscopy is performed on a terahertz (THz) frequency quantum cascade laser (QCL) with two broadband THz pulses. Gain switching is used to amplify the first THz pulse and the second THz pulse is used to probe the system. Fourier transforms are taken with respect to the delay time between the two THz pulses and the sampling time of the THz probe pulse. The two-dimensional spectrum consists of three peaks at (ω = 0, ω = ω), (ω = ω, ω = ω), and (ω = 2ω, ω = ω) where ω denotes the lasing frequency. The peak at ω = 0 represents the response of the probe to the zero-frequency (rectified) component of the instantaneous intensity and can be used to measure the gain recovery.

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Section: Measurement Set-upmentioning

confidence: 99%

Two-dimensional coherent spectroscopy of a THz quantum cascade laser: observation of multiple harmonics

Markmann¹,

Nong²,

Pal³

et al. 2017

Opt. Express

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“…Both a reference MM and a hybrid waveguide are cleaved into L = 3.5 mm long and 2 mm wide pieces. In order to experimentally access the dispersion and thereby the GVD features of the DM waveguide section a THz time domain spectroscopy setup is employed [35,36]. According to Fig.…”

Section: Experimental Measurement: Gvd and Chirp Analysismentioning

confidence: 99%

Broadband terahertz dispersion control in hybrid waveguides

Fobbe¹,

Markmann²,

Fobbe³

et al. 2016

Opt. Express

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Dispersion control is a key objective in the field of photonics and spectroscopy, since it enhances non-linear effects by both enabling phase matching and offering slow light generation. In addition, it is essential for frequency comb generation, which requires a phase-lock mechanism that is provided by broadband compensation of group velocity dispersion (GVD). At optical frequencies, there are several well-established concepts for dispersion control such as prism or grating pairs. However, terahertz dispersion control is still a challenge, thus hindering further progress in the field of terahertz science and technology. In this work, we present a hybrid waveguide with both broadband, tuneable positive and more than octave-spanning negative terahertz GVD on the order of 10^-22 s²/m, which is suitable for either intra- or extra cavity operation. This new terahertz device will enable ultra-short pulse compression, allow soliton propagation, improve frequency comb operation and foster the development of novel non-linear applications.

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“…Hence, the response from the sample is purely due to metamaterials. A Ti:Sa laser with an 80 fs pulse duration (a centre wavelength of 800 nm) and a repetition rate of 80 MHz is used to generate the THz radiation by exciting an inter-digitated photoconductive antenna [9] processed on a GaAs substrate. A fixed DC bias is applied on the antenna.…”

Section: Different Types Of Field-effect Transistors -Theory and Applmentioning

confidence: 99%

“…Stacking of quantum wells can further enhance the response of intersubband resonance (ISR), and such designs are the key for various applications like photodetectors or intersubband lasers [6]. One of the very common and sophisticated examples in this regard is the quantum cascade laser [7][8][9], which is based on the cascade phenomena and intersubband transitions across many layers of quantum wells. Such compact and powerful lasers are used for practical applications in THz spectroscopy [10][11][12][13], sensing technology [14,15], biomedical applications [16,17] and also in security applications [11,18].…”

Section: Introductionmentioning

confidence: 99%

Quantum Confinement in High Electron Mobility Transistors

Pal¹,

Valentin²,

Ludwig³

et al. 2017

Different Types of Field-Effect Transistors - Theory and Applications

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Modulation-doped semiconductor nanostructures exhibit extraordinary electrical and optical properties that are quantum mechanical in nature. The heart of such structures lies in the heterojunction of two epitaxially grown semiconductors with different band gaps. Quantum confinement in this heterojunction is a phenomenon that leads to the quantization of the conduction and the valence band into discrete subbands. The spacing between these quantized bands is a very important parameter that has been perfected over the years into device applications. Most of these devices form lowdimensional charge carriers that potentially allow optical transitions between the subbands in such nanostructures. The transition energy differences between the quantized bands/levels typically lie in the infrared or the terahertz region of the electromagnetic spectrum and can be designed according to the application in demand. Thus, a proper understanding and a suitable external control of such intersubband transitions (ISTs) are not only important aspects of fundamental research but also a necessity for optoelectronic device applications specifically towards closing the terahertz gap.

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Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes

Cited by 9 publications

References 30 publications

Two-dimensional coherent spectroscopy of a THz quantum cascade laser: observation of multiple harmonics

Two-dimensional coherent spectroscopy of a THz quantum cascade laser: observation of multiple harmonics

Broadband terahertz dispersion control in hybrid waveguides

Quantum Confinement in High Electron Mobility Transistors

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