Invention:
For many applications, the output of a laser diode is coupled into an optical fiber to direct the light beam more easily. This fiber can be doped with rare earth metals such as Erbium to increase efficiency and absorption. Instead of using Erbium (Er3+) exclusively for doped fiber lasers, this method proposes the use of codoped Er3+ fiber lasers with Holmium (Ho3+) and Dysprosium (Dy3+). Current Er3+-doped lasers can only reach the 2.8-2.9 micron wavelength range but deliver a high power output. Ho3+/ Dy3+-doped lasers lack the power output of Er3+-doped lasers but are able to reach wavelength regions above 3 microns. By codoping Ho3+ and Dy3+with Er3+, compact all-fiber lasers above 3-micron meter can be developed with the use of readily available, high power, and efficient diode lasers.
Background:
Erbium is the most common rare earth element used in fiber lasers because the available atomic energy levels for excitation and decay better match light energy output (wavelengths) from cheaper diode sources. Fiber laser beam quality is high and the power output is over 6kW, which is very high compared with a traditional gas or crystal laser. Fiber lasers are also efficient (70%-80%) which means they consume less power and are easier to cool. Because the beam remains focused within a fiber, it can be very small which makes fiber lasers an excellent source for laser cutting.
A fiber laser requires an energy source, such as 980nm pumped light from a laser diode coupled to the fiber, to produce the beam. This light energy source stimulates emission in the doped material of the fiber which creates the beam along the laser fiber. Emission is generally lower energy than the pumped energy – 1535nm compared with 980nm – but some heavy metal fluoride upconversion fiber lasers (ZBLAN) use multiple stimulated phonon transitions to produce higher energy emissions (480nm output with 1140nm input). ZBLAN fiber lasers may also be used for longer wavelength emission in the “eye-safe” region beyond 1400nm though output power remains lower than for shorter wavelengths.
Applications:
- Material processing
- Medical
- Sensing
- Imaging
- Spectroscopy
- Defense (directed energy)
- Telecommunications
Advantages:
- 3-micron meter wavelength regions
- Cost efficient
- Energy efficient
