Optics 101

Chromium Doped Zinc Chalcogenide Lasers – Properties and Applications

Chromium belongs to the group of transition elements in the periodic table; its ions of various charges are often used as dopants of the active lasing mediums. The addition of the chromium Cr2+ ion to ZnSe as the active medium causes emissions in the range of 1.9 to 3.5µm. An active lasing medium, which is doped with chromium ions, exhibits strong electron-phonon interaction, and has a large gain bandwidth. Hence, such lasers are called vibronic lasers.

For high output from the Cr:ZnSe laser the right magnitude of power needs to be maintained. The pumping source is another laser, the Tm fiber laser. The edges of the active medium, which is the chromium doped ZnSe crystal, are cut at the Brewster angle, in order to achieve the maximum wavelength.

Laser Properties

Laser Properties
Laser type Solid
Pump source Other Laser (Tm Fiber)
Operating wavelength 2.2 – 2.8µm

Physical and Chemical Properties

Physical and Chemical Properties
Chemical formula Cr:ZnSe
Crystal structure Cubic
Melting point 1525°C
Thermal conductivity 18 W/mK


The primary applications of the chromium doped ZnSe laser are in defense related operations, such as MWIR laser radar, counter measure against heat-seeking missiles, etc.

Some of the other applications of the Cr:ZnSe laser are listed below:

  • Spectroscopy
  • Radar sensing
  • As seeding or pumping sources for middle infrared optical parametric oscillators
  • Medical procedures


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