23 Aug 2011 Composite laser crystals (sometimes called hybrid laser crystals) are laser crystals which have been fabricated by combining different parts. Typically, adhesive-free diffusion bonding of carefully prepared crystal surfaces is used, e.g., to combine an Nd:YAG or Yb:YAG crystal with an undoped YAG crystal. The same can be done e.g. with Nd:YVO4. Another possibility is to bond a Cr:YAG crystal (a saturable absorber material for passive Q switching) to Nd:YAG. In other cases, a nonlinear crystal material for nonlinear frequency conversion is bonded to a laser crystal. Composite gain media can also be made of glasses and from ceramics.
Lasertec Diffusion bonding means that the two parts that are bonded together diffuse into one another and they become as one single crystal. The technology of diffusion bonding includes the following steps:
1. Perfect optical contact between the crystals to be bonded.
2. Heating up of the two parts very slowly (within 24 hours or even more), to a very high temperature, probably 2/3 of the melt temperature or more, and exerting pressure to press the two parts together.
3. Keeping the bonded crystals for certain period of time at this high temperature, so that diffusion takes place.
4. Slowly cooling the crystals (24 hours or even more) down to room temperature.
Nd:YVO4 Doping 0.2-3%
Nd:YAG Doping 0.5-1.1%
Wavefront Distortion Orientation ±0.5deg.
Dimensional Tolerance ± 0.1mm
Surface quality 10/5 Scratch/Dig per MIL-O-13830B
Flatness Clear Aperture > Central 90%
Parallelism < 10 arc sec.
Intrinsic Loss < 0.1% cm -1
Coating: AR or HR coating |
