Broadly tunable single-mode mid-infrared quantum cascade lasers

Abstract

In this paper, we review the recent progress in broadly tunable single-mode mid-infrared quantum cascade lasers (QCLs). With a brief introduction on various applications of broadly tunable single-mode mid-infrared QCLs, we first categorize these lasers based on their configurations and tuning schemes. Then recent progress in each scheme is investigated, together with detailed discussions. Furthermore, the pros and cons of different approaches are compared, and the opportunities and challenges for future developments from our point of view are listed. Last but not least, potential new directions and prospects for obtaining broadly tunable single-mode characteristics are also provided. It is foreseeable that, with the development of high performance broadly tunable single-mode mid-infrared QCLs, more applications could be exploited in the near future with new phenomena to be discovered.

Quantum cascade lasers (QCLs) in biomedical spectroscopy

“…The wavelength can be freely designed over almost 3 octaves of the photon emission frequencies using one single material system as active medium. While the material system based on InGaAs/AlInAs heterostructure grown on InP substrate is the most mature technology and compatible with mass production requirements, 22 active region designs based on InAs/AlSb have been presented. 23 The position of the emission center wavelength of a laser within the mid-IR region is determined by the energy difference of the two energy states corresponding to the intra-band radiative transition (see Fig.…”

Photonic Engineering Technology for the Development of Terahertz Quantum Cascade Lasers

“…One of the most significant features of QCLs is the possibility to tune the single-mode emission over a broad frequency range, [41] which is desired for many applications, for example, in THz frequency range as a local oscillator in the heterodyne receiver or as sources for chemical/biomolecular sensing and spectroscopy. [33] On the one hand, it is possible to directly adopt the spectral control concepts well-developed in the short wavelength range.…”

“…The frequency of a single-mode DFB laser can only be tuned for ≈12 GHz with heat-sink temperature modulated from 8 to 97 K. [54] Current-injection tuning resulting from the refractive index change of the gain material due to the Joule heating effect is even weaker. [41] A discrete frequency tuning over 160 GHz can be achieved at around 2.9 THz, [88] whereas much more efforts are Adv. To enhance the frequency tuning range, complicated optical cavities, such as two-section coupled-cavity structures, [87] aperiodic gratings within a standard FP cavity, [88] were utilized to expand the tuning capability based on the so-called Vernier effect.…”

“…To enhance the frequency tuning range, complicated optical cavities, such as two-section coupled-cavity structures, [87] aperiodic gratings within a standard FP cavity, [88] were utilized to expand the tuning capability based on the so-called Vernier effect. [41] A discrete frequency tuning over 160 GHz can be achieved at around 2.9 THz, [88] whereas much more efforts are Adv. Optical Mater.…”

Development of suspended core soft glass fibers for far-detuned parametric conversion

“…Cr 2+ : ZnSe and Fe 2+ : ZnS(e) are also attractive for MIR devices, opening operation wavelength ranges from 2 um to 3.5 µm and around 3.5 µm to 5 µm, respectively [9]. The quantum cascade lasers, where output is produced by consecutive radiative transitions within the conduction band, instead of the electron-hole recombination, are yet another alternative, with wavelength coverage between 3 µm to 25 µm [10].High brightness MIR light can be obtained also with the use of nonlinear optical frequency conversion of pump and signal wavelengths. These would be typically available from mature light sources, i.e.…”