What is a DPSS Laser?
DPSS Laser or diode-pumped solid-state laser is a solid-state laser made by pumping a solid gain medium, for example, a ruby or a neodymium-doped YAG crystal, with a laser diode. DPSSLs have advantages in compactness and efficiency over other types, and high power DPSSLs have replaced ion lasers and flash lamp-pumped lasers in many scientific applications, and are now appearing commonly in green and other color laser pointers.
How does a DPSS Laser Work?
The wavelength of laser diodes is tuned by means of temperature to produce an optimal compromise between the absorption coefficient in the crystal and energy efficiency (lowest possible pump photon energy). As waste energy is limited by the thermal lens this means higher power densities compared to high-intensity discharge lamps.
High power lasers use a single crystal, but many laser diodes are arranged in strips (multiple diodes next to each other in one substrate) or stacks (stacks of substrates). This diode grid can be imaged onto the crystal by means of a lens. Higher brightness (leading to better beam profile and longer diode lifetimes) is achieved by optically removing the dark areas between the diodes, which are needed for cooling and delivering the current. This is done in two steps:
The "fast axis" is collimated with an aligned grating of cylindrical micro-lenses.
The partially collimated beams are then imaged at reduced size into the crystal. The crystal can be pumped longitudinally from both end faces or transversely from three or more sides.
The beams from multiple diodes can also be combined by coupling each diode into an optical fiber, which is placed precisely over the diode (but behind the micro-lens). At the other end of the fiber bundle, the fibers are fused together to form a uniform, gap-less, round profile on the crystal. This also permits the use of a remote power supply.
DPSS laser, with high output power stability, ultra compact, long lifetime, which are widely used in:
- spectrum analysis
- laser printing
- fluorescence excitation
- laser treatment
- laser medical treatment
- scientific experiment