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The emission wavelength of the tunable diode laser, viz. VCSEL, DFB, etc., is tuned over the characteristic absorption lines of a species in the gas in the path of the laser beam. This causes a reduction of the measured signal intensity due to absorption, which can be detected by a photodiode , and then used to determine the gas concentration ...
The dye laser is considered to be the first broadly tunable laser. A tunable laser is a laser whose wavelength of operation can be altered in a controlled manner. While all laser gain media allow small shifts in output wavelength, only a few types of lasers allow continuous tuning over a significant wavelength range.
It is also a widely used technique for a variety of other applications, e.g. within the field of optical frequency metrology or in studies of light matter interactions. The most common technique is tunable diode laser absorption spectroscopy (TDLAS) which has become commercialized and is used for a variety of applications.
Optically pumped semiconductor laser 920 nm-1.35 μm Laser diode Projection, life sciences, forensic analysis, spectroscopy, eye surgery, laser light shows. The lasing medium is a semiconductor chip. Frequency doubling or tripling is typically done to produce visible or ultraviolet radiation. Power levels of several watts are possible.
Part of a Ti:sapphire oscillator. The Ti:sapphire crystal is the bright red light source on the left. The green light is from the pump diode. Titanium-sapphire lasers (also known as Ti:sapphire lasers, Ti:Al 2 O 3 lasers or Ti:sapphs) are tunable lasers which emit red and near-infrared light in the range from 650 to 1100 nanometers.
A tunable laser could function at any wavelength, eliminating the cost of manufacturing and the logistics of maintaining up to 80 different parts. [6] This is the case since tunability offers a more flexible and less costly operation. Given the large venture capital investments of the time, dozens of approaches and technologies were proposed.
The difference is the choice of the laser wavelength, which must be selected to match the energy of an electronic transition in the sample. A tunable laser is thus often used for resonance Raman spectroscopy, since a single laser can be used to generate many possible excitation wavelengths to match different samples. [8]
In tunable laser resonators intracavity beam expansion usually illuminates the whole width of a diffraction grating. [2] Thus beam expansion reduces the beam divergence and enables the emission of very narrow linewidths [ 3 ] which is a desired feature for many analytical applications including laser spectroscopy.