As efficiency and power continue to increase, laser diodes will continue to replace traditional technologies, changing the way existing things are handled and creating new things at the same time. Similarly, there is limited awareness of the dramatic development of high power semiconductor lasers. The industry demonstrated for the first time in 1962 that electrons were converted to 500mw laser pointer, and a great deal of progress ensued, all of which led to significant improvements in the conversion of electrons to high-yield laser processes. These improvements support a range of important applications, including optical storage, optical networking, and a wide range of industrial applications.
The innovations of the past decades have brought exciting improvements. In particular, the improvements in brightness are excellent. In 1985, the state of the art high-power semiconductor lasers were able to couple 105 milliwatts of power into a 105-micron core-diameter fiber. State-of-the-art high power semiconductor lasers can now produce over 250 watts and have a single wavelength of 105 micron optical fiber - a 10x increase every eight years.
The improvement of high-power semiconductor 200mw laser pointer brightness has promoted the development of various unforeseen technologies. Although this trend continues the need for more innovation, but there is reason to believe that innovation in semiconductor laser technology is far from complete. Well-known physics can further enhance the performance of semiconductor lasers through continuous technological developments.
For example, quantum dot gain media can significantly improve efficiency over current quantum well devices. Slow axis brightness offers another order of magnitude improvement potential. New packaging materials with improved heat dissipation and extended matching will provide the enhancements needed for continuous power regulation and simplified thermal management. These key developments will provide a roadmap for the development of high-power semiconductor lasers for decades to come.
Improvements in high-power semiconductor lasers make it possible to develop downstream 30mw laser pointer technology; in the downstream laser technology, semiconductor lasers are used to excite (pump) doped crystals (diode-pumped solid-state lasers) or doped optical fibers (fiber lasers).
Although semiconductor lasers provide high efficiency, low cost laser energy sources, there are two key limitations: They do not store energy and their brightness is limited. Basically, these two lasers need to be used in many applications: one for converting electricity into a laser emission and the other for enhancing the brightness of the laser emission.
Diode-pumped solid-state lasers. In the late 1980's, the use of pumped solid-state 50mw laser pointer with semiconductor lasers started to gain popularity in commercial applications. Diode-pumped solid-state lasers (DPSSL) have dramatically reduced the size and complexity of thermal management systems (primarily recirculating chillers) and have resulted in modules that traditionally incorporate arc lamps for pumping solid-state laser crystals.
The choice of semiconductor laser wavelengths is based on their overlap with the spectral absorption characteristics of the solid-state laser gain medium; the thermal load is greatly reduced compared to the broadband emission spectrum of an arc lamp. Due to the popularity of 1064 nm neodymium-based lasers, the 808 nm pump wavelength has become the largest wavelength in semiconductor lasers for more than 20 years. Fiber lasers provide a more efficient way of converting the brightness of high power semiconductor lasers. Although wavelength multiplexing optics can convert relatively low-brightness semiconductor lasers into brighter semiconductor 10mw laser pointer, this is at the expense of increased spectral width and optical mechanical complexity. Fiber lasers have proven to be particularly effective in photometric conversion.