Cr4:YAG Passive Q-Switch Crystals
Cr4+:YAG crystals have several advantages when compared to traditional Passive Q-switching choices such as organic dyes and colour centres materials. Crystal Passive Q-switch is preferred for simplicity of manufacturing and operation, low cost, and reduced system size and weight. Cr4+:YAG is chemically stable, UV resistant and it is durable. Cr4+:YAG will operate over a wide range of temperatures and conditions. The good thermal conductivity of Cr4+:YAG is well suited for high average power applications.
Excellent results have been demonstrated using Cr4+:YAG as a passive Q-switch for Nd:YAG lasers. The saturation fluence was measured to be approximately 0.5 J/cm2. The slow recovery time of 8.5 µs, as compared to dyes, is useful for the suppression of mode locking. Q-switched pulsewidths of 7 to 70 ns and repetition rates of up to 30 Hz have been achieved. Laser Damage Threshold tests showed AR coated Cr4+:YAG passive Q-switches exceeded 500 MW/cm2.
The optical quality and homogeneity of Cr4+:YAG is excellent. To minimise insertion loss the crystals are AR coated. Cr4+:YAG crystals are offered with a standard diameter, and a range of optical densities and lengths to match your specifications.
Optical Properties and Dimensions
| Diameter | 6.35 mm |
| 0 mm / +0.05 mm | |
| Typical Length | 2 mm to 10 mm |
| Parallelism | 30 arc-sec. max |
| Flatness | λ/2 at 632 nm Max. |
| Refractive Index | 1.82 at 1.064µm |
| Standard Optical Densities | 0.40 +/- 10% |
| 0.50 +/- 10% | |
| 0.60 +/- 10% | |
| 1.00 +/- 10% | |
| Saturation Fluence | near to 0.5 J/cm2 |
| Recovery Time | 8.5 µs |
| Repetition Rate | > 30 Hz |
| AR coating | 0.3% per surface |
| Damage Threshold | > 500 MW/cm2 |
| Chemical Formula | Y3Al5O12:Cr4+ |
| Orientation | <111 > cubic |