Etalons, beam splitter cubes, Faraday isolators, retroreflectors, collimators, and lenses with volume Bragg gratings belong to the group of special optics. These optical components are used in special laser applications.
Volume Bragg Gratings (VBG)
To stabilize the wavelengths of high power laser diodes, laser diode arrays, and in measurement devices.
Both efficiency and lifetime of high power multi mode laser diodes improve significantly when used together with Volume Bragg Gratings (VBG) from PD-LD, Inc. At the same time, the bandwidth is reduced and the wavelength stabilized, making them virtually temperature independent.
In general a VBG can be used with any wavelength and any optical output power - with single devices, linear arrays and multi array stacks
A normal high power laser diode without VBG typically has an FWHM of 3 to 6 nm, a wavelength tolerance of +/- 3 nm, and a temperature dependence of the wavelength of 0.3 nm/K. Together with a VBG the FWHM value is reduced to less than 0.5 nm, the tolerance to +/- 0.5 nm, and the temperature dependence to 0.01 nm/K. In this way the laser diode comes much closer to the ideal monochromatic beam source than in the past.
The following properties are very interesting for a large number of important applications:
- Highly efficient pumping of solid state lasers
- Pumping of new lasers (e.g. thin disk lasers) that require a very narrow pump wavelength
- Increase in lifetime of pump arrays by reducing or even eliminating the red shift caused by aging
- Sensor technology, chemical analysis, and certain medical applications that rely on exact center wavelengths.
In principal VBG can be used with laser diodes of all wavelengths and every power level for single emitters, linear arrays, and multi array stacks.