Comparison of laser crystals
This article mainly introduces the characteristics and applications of various common crystals, and compares them.
Form of Comparison of Crystals
| wdt_ID | Types | Features | Application |
|---|---|---|---|
| 1 | Pr:YLF crystal | Has the properties required to achieve lasing in the visible spectral range | Diode-pumped solid-state lasers for precision and efficient processing of metals such as copper or gold, entertainment and science |
| 2 | Ho:YLF crystal | The 5I7 level has a long lifetime and therefore has strong performance in Q-switching operation | Remote Sensing and Contaminant Detection military |
| 3 | Tm,Ho: KYW crystal | Large and broad polarized absorption and emission bands, efficient energy transfer TM3+→Ho3+, high doping concentration low concentration quenching | 2 μm laser for remote sensing (radar technology), metrology and medical applications; pump source for mid-infrared optical parametric oscillators (OPOs) |
| 4 | Nd:KGW crystal | Suitable for generating picosecond light pulses, ideal for diode-pumped lasers; high storage density and low lasing threshold; high-efficiency Raman converters | Diode-pumped Q-switched laser, emitting in the "eye-safe" spectral range of laser rangefinders; Raman converter |
| 5 | Nd:YLF crystal | 4F3/2 Neodymium level has long lifetime; softer and more brittle than Nd:YAG; Nd:YLF (a-shape) crystals used inside laser optical resonators are self-polarizing | Continuous wave and pulsed operation at 1047nm and 1053nm for material processing, welding, cutting |
| 6 | Yb:YAG crystal | Simple electronic structure excludes excited state absorption and also excludes various detrimental quenching processes; broad absorption band at 940 nm; long lifetime at 2 F 5/2 energy level; low quantum defects | Material Processing, Micromachining, Welding, Cutting; Efficient High Power Thin Disc Lasers |
| 7 | Yb:CaF2 crystal | Isotropic crystal (cubic symmetry); low quantum defects; long lifetime at 2 F 5/2 energy level; broad light transmission; low dispersion behavior; limited nonlinear effects under intense laser irradiation | Diode-pumped femtosecond solid-state laser designed to generate high-energy pulses; ultrashort pulses with ultra-high average power |
| 8 | Yb:YVO4 crystal | Simple electronic structure excludes excited state absorption and also excludes various detrimental quenching processes; broad and smooth emission spectrum; low quantum defects | High-power CW, Q-switched and mode-locked lasers; thin disk lasers |
| 9 | Yb:YAB crystal | Self-doubling laser crystal; high thermal conductivity; wide absorption bandwidth around 976 nm; high absorption and emission cross sections; low quantum defects | High Power Continuous Wave Lasers; Mode Locked Femtosecond Lasers; Continuous Wave and Mode Locked Self Frequency Doubling Lasers |
| 10 | Yb:YAP crystal | Biaxial orthorhombic crystal; high absorption cross section dependent on crystal orientation; high thermal conductivity; low quantum defects | Femtosecond lasers and regenerative amplifiers; CW and passively mode-locked thin-disk lasers |
Nd:YAG crystal
Nd:YAG crystals have the characteristics of good mechanical properties, high gain, good thermal properties and optical uniformity, and are widely used in scientific research, industry, military and other fields. The relatively small gain bandwidth of Nd:YAG crystal can achieve high gain efficiency and relatively low lasing threshold. Its excellent thermal and mechanical properties allow the growth of crystals with high optical quality and large diameters. Its appearance has made solid-state lasers vigorously developed and successfully commercialized. Nd:YAG crystals absorb at 808nm and typically emit light around the peak at 1064nm, but there are also transitions around 940nm, 1120nm, 1320nm and 1440nm.
In high-power CW lasers and solid-state lasers, as well as military lasers, Nd:YAG crystal is one of the main application materials. The current main applications are as follows:
- Manufacture for engraving and etching various metals, plastics;
- Medical – such as endoscopy, urology, neurosurgery, gynecology, dermatology, dental surgery and general surgery to treat various diseases such as cancer and liver disease, etc.;
- rangefinders and lighting equipment;
- For engineering applications such as resistance, trimming, drilling, etc.;
- for process visualization technology;
- For spectral analysis.
Nd:YVO4 crystal
The Nd:YVO4 crystal is uniaxial and only emits linearly polarized light, avoiding the influence of unnecessary birefringence on frequency doubling. It is very suitable as a medium for high repetition rate Q-switched lasers and low threshold CW lasers.
The absorption peak wavelength of Nd:YVO4 crystal is 808nm, and the emission is 914nm, 1064nm and 1342nm.
Advantages of Nd:YVO4 comparison:
Compared with Nd:YAG, the stimulated emission cross-section of Nd:YVO4 at 1064 nm is several times larger, and the stimulated emission cross-section at 1342 nm is more than twelve times larger than that of Nd:YAG. If a pulsed or continuous wave laser is to be constructed, Nd:YVO4 is a good medium in place of Nd:YAG.
The absorption coefficient of Nd:YVO4 is greater than that of Nd:YAG, and using the same 808 nm diodes, if Nd:YVO4 is used, these diodes can be used at lower power, increasing the life of the diodes.
Disadvantages of Nd:YVO4 compared to Nd:YAG:
The up-state lifetime of Nd:YVO 4 is about 2.5-3 times shorter than that of Nd:YAG. This means that it is difficult (sometimes even impossible) to obtain pulse energies as high as Nd:YAG during Q-switching
Applications: low and medium power lasers, machine vision, spectroscopy, medical lasers
Ti:Al2O3 crystal
Titanium sapphire (Ti:Al2O3) crystal has high stability and very long service life, and can be used in laser systems with a wavelength range of 600-1050 nm to realize femtosecond laser pulses. In June 1982, Peter Moulton constructed and invented the first titanium:sapphire-based laser at the MIT Lincoln Laboratory.
The absorption band of titanium:sapphire is centered at 490 nm, making it suitable for a variety of laser pumping light sources – argon-ion, frequency-doubled Nd:YAG and YLF, copper vapor lasers. With a fluorescence lifetime of 3.2 μm, short-pulse flash lamps can efficiently pump Ti:sapphire crystals in powerful laser systems.
Applications: Medical Laser Systems, LiDAR, Laser Spectroscopy.