Quantum cascade lasers (QCLs) are known as one of the most important inhibitor supplier and influential laser sources for mid-infrared spectroscopy [1,2]. A QCL is a unipolar semiconductor laser based on intersubband transitions in a periodically repeated quantum well structure. Their demonstrated narrow spectral line width and selleckbio the possibility of choosing the emission wavelength in a broad spectral range in 2.5�C300 ��m by quantum engineering are key properties. Mid-infrared QCLs are compact devices that can emit at room-temperature with high power levels [3]. QCLs can achieve a wall-plug efficiency exceeding50 % [4,5] and can be designed to cover a broad spectral range, while emitting spectrally single mode.
This is important for chemical sensing to identify different molecules with great selectivity and facilitated calibration.
Inhibitors,Modulators,Libraries This can be realized Inhibitors,Modulators,Libraries by a bound-to-continuum design, which inherently has a broad Inhibitors,Modulators,Libraries gain spectrum, leading to an electro-luminescence spectrum as broad as 295 cm?1[6]. The gain bandwidth can be further increased with multiple strongly coupled upper laser levels [7] or by using heterogeneously designed cascades [8]. With this approach, a tunable single mode laser emission beyond 400 cm?1 was demonstrated using an Inhibitors,Modulators,Libraries external cavity [9]. To achieve more compact sensors,distributed feedback ridge arrays or surface emitting ring cavity arrays, with a reported spectral range of 220 cm?1 and 180 cm?1 in [10] and [11] can be used.
DFB arrays are perfect for in-plane on-chipsensing, where the surface emitting rings have the advantage a smaller divergence < 3 �� and therefore do not necessarily require external lenses in miniaturized systems [12].
Inhibitors,Modulators,Libraries Alternatively, single Inhibitors,Modulators,Libraries Inhibitors,Modulators,Libraries mode emission can be Anacetrapib achieved without gratings utilizing coupled ridge cavities [13], a coupled active ring resonator [14] or Mach�CZehnder interferometer type cavities [15]. Without the need of high quality lithography, their processing is the same as for a simple ridge laser. These methods are thus promising forcost-effective Inhibitors,Modulators,Libraries devices.Commonly, MIR Batimastat spectroscopy setups are realized using broadband MCT-detectors (HgCdTe).More recently, spectroscopic setups have been realized using quantum cascade detectors QCDs [16].
As indicated by its name, QCDs are the counterpart of QCLs, based on the same principle [17]. Without the need of cryogenic cooling QCDs are ideal for portable low-power applications.
Furthermore, the response of QCDs is extremely fast and can be used to observe the peak power of nanosecond www.selleckchem.com/products/BAY-73-4506.html laser pulses [18]. This helps to reduce the total power consumption below 10 mW, when the laser operates in pulsed mode. The fact that QCDs can operate at room our website temperature and are based on the same principle as QCLs makes them a perfect candidate for integration.As the total absorption scales with the interaction length, it is sometimes difficult to observe measurable signals from light interactions with molecules at chip-scale dimensions.
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