Researchers have developed a QCL DFB continuous laser for gas detection

Alpes Laser was founded in 1998 in Nazhatel, Switzerland and was the first company to bring quantum cascade lasers to the market. It released its first continuous laser in 2001 and its first high gain laser in 2009, thus maintaining this priority position.

In 2004, the first commercial laser was introduced.

Principle: In a single mode laser, the grating is etched into the active region to force the laser to operate at a very specific wavelength determined by the periodicity of the grating. Therefore, the laser emits in a unique spectral mode, which can be slightly adjusted by changing the temperature of the active region.

Gas detection

Continuous single mode lasers have a narrow linewidth, making them an ideal choice for gas detection. They can be adjusted within a maximum range of 10 cm-1; There are multiple modulation schemes available for different purposes. CW-DFB lasers (for continuous wave and distributed feedback) are mainly used in spectroscopy.

Available wavelengths between~625cm-1 and 2500cm-1 (4-16 μ m) Between, the power is 5-100mW. These lasers operate at room temperature. They are provided in the form of chips, base chips, or boxes, with functions such as temperature control, collimation, and fiber coupling.

Other applications: dual frequency comb high-resolution spectroscopy

A quantum cascade laser frequency comb is a device that emits light over a wide spectrum composed of equidistant peaks in the frequency space. Due to the fixed distance between these peaks, which is usually given by the repetition rate of ultrashort pulse sequences, they can be used as frequency domain benchmarks for frequency comb spectra.

In the mid infrared region, quantum cascade lasers that have been specifically studied for optical dispersion have been proven to emit wide and powerful optical frequency combs. Like ultra short pulse lasers, the mode spacing of QCL combs is given by the cavity length. However, in the case of QCL, the periodic modulation in the time domain is FM, not AM, so the output power is constant.

Unlike other comb like technologies, QCL based combs integrate pump lasers and microcavities into their waveguides. This makes it a very compact source. Based on QCL technology, these comb shaped devices can be manufactured across MWIR and LWIR.

The double comb spectrum depends on two local oscillators (OFCs), with slightly different peak spacing. The heterodyne beat frequency of two such combs consists of equally spaced peaks, representing the spectrum of laser in the RF domain.

QCL based dual comb spectroscopy provides the possibility of collecting high-resolution spectra in a wide spectral range of tens of cm-1 and in extremely short acquisition time (i.e. near real-time) at the µ s level. This technology combines the advantages of DFB QCL (i.e. narrow linewidth and mode hopping free tuning) with the large wavelength coverage of external cavity QCL.

Source: Laser Network