Laser crystals

Yb:YAG

Yb:YAG is well suited for high power laser applications. Its advantage is a wide pump band tolerant to pump diode wavelength variations and an excellent emission cross section.

Yb:YAG
Emission wavelength	1030 nm
Pump wavelength	941 nm
Fluorescence lifetime	0.95 - 1.2 ms
Emission cross section	2.1 x 10-20 cm2 (± 10%)

Our standard offer of Yb doped YAG crystals includes:

• Yb dopant concentrations from 1 at. % up to 15 at. % of Yb/Y
• Rod diameters from 2 up to 10 mm
• Rod lengths up to 100 mm
• Variety of anti-reflection, partial or high reflection coatings

V:YAG saturable absorber

YAG crystals doped with three-valence vanadium V³⁺ in tetrahedral positions hint at being efficient passive absorbers for lasers operating in 1.3 µm region. The efficient Q-switching and modelocking has been obtained with a number of active media such as Nd:YAG, Nd:YAP, Nd:KGW, Nd:YVO₄ under flash-lamp and diode pumping.

V:YAG properties at 1.3 µm
Ground-state absorption cross-section	7.2 x 10-18 cm2
Excited-state absorption cross-section	7.4 x 10-19 cm2
Recovery time	5 - 22 ns
Absorption coefficient (standard V3+ concentration)	2.2 cm-1

V:YAG plates are available in a wide range of initial transmission values and with diameters between 2 - 10 mm.

An alignment free microchip laser design consisting of saturable + active + undoped parts can be designed upon request. The dielectric mirrors can be placed directly on the crystal faces.

For more information see

                                         V:YAG michrochip laser

Tm:YAP & Tm:YAG

Tm doped crystals embrace several attractive features that nominate them as the material of choice for solid-state laser sources with emission wavelength around 2 µm. There is a self-quenching mechanism between the ³H₄ and ³F₄ levels that produces two excitation photons in the upper laser level for one absorbed pump photon. This makes the laser potentially very efficient with high quantum efficiency.

The absorption band of Tm:YAP between the ³H₆ and ³H₄ levels with a peak at 795 nm is easily accessible with high power AlGaAs laser diode pumping. Also, the 4-nm wide absorption peak of Tm:YAP is broader compared to Tm:YAG, resulting in better tolerance to pump diode wavelength variations.

The emission wavelength of Tm:YAP laser depends on crystal orientation. Crystals cut along the "a" or "b" axis (ref. to Pbnm space group) are mostly used.

Tm:YAP	"a" cut	"b" cut
Absorption peak	794.8 nm	793.5 nm
Peak effective pump absorption coeficient	aa = 3.6 cm-1	aa = 3.3 cm-1
Emission wavelength	1.98 µm	1.94 µm

Tm:YAG finds its application in laser radar and other atmospheric sensing applications due to its operating wavelength at 2013 nm. The absorption band peaking at 785 nm is suitable for pumping by semiconductor diodes.

Our standard offer of Tm doped YAP and YAG crystals includes:

• Tm dopant concentrations from 1 at. % up to 8 at. % of Tm/Y
• Rod diameters from 2 mm up to 7 mm
• Rod lengths up to 100 mm
• Variety of anti-reflection, partial or high reflection coatings in the range of 2 µm
  
  

Graded reflectivity laser mirrors 

R(r) = R₀ exp (-2(r/w₀)^N)

Working wavelength:	1064 nm
Reflectivity profile:	nearly Gaussian or super-Gaussian with specified order N
Size of reflecting  area w0:	typically f0.5 to 10 mm (at Ro/e2)
Central reflectivity R0:	from region 5 % to 80 % (+/-1 % to +/-5% depending on the reflectivity level)
Residual reflectivity:	<1/20 of the central reflectivity or <0.5%
Second side:	appropriate AR-coating

Other wavelengths and reflectivity levels on request.

CRY18 - The new scintillation material 

CRY18 is a new mixed rare-earth silicate single crystal of medium density featuring high light yield and short decay time. Scintillation wavelength is about 425 nm which is preferred for PMT readout.

Advantages:

• medium density
• fast decay time
• preffered for PMT redout
• very good machining property 

Main usage:

• detectors for Electron Microscopy
• detectors for X ray, gamma and beta ray
• high spatial resolution Imaging Screens for X ray, gamma, beta and UV

For more information see Technical parameters (.pdf)

CRY19 - The new scintillation material 

CRY19 is a new mixed rare-earth silicate single crystal of high density featuring high light yield and short decay time. Its scintillation wavelength is about 420 nm which is preferred for PMT readout. It is a preferred choice for Gamma ray detectors.

Advantages:

• high density
• fast decay time
• preffered for PMT redout
• very good machining property

Main usage:

• Gamma and beta ray detectors
• PET and SPECT matrixes
• high spatial resolution Imaging Screens for X ray, gamma, beta and UV

For more information see Technical parametrs (.pdf)

LuAG:Ce - The new scintillation material 

LuAG:Ce, Lutetium Aluminum Garnet activated by cerium (chemical formula Lu3Al5O12), is a relatively dense and fast scintillation material. Its density of 6.73 g/cm3 is about 94% of the density of BGO (7.13 g/cm3). Its decay time is much faster (70 ns) than that of BGO (300 ns). This is of advantage in time dependent and coincidence measurements. The wavelength of scintillation emission is about 535 nm, which is ideal for photodiode and avalanche diode readout. The material can also be used for imaging screens, similarly to YAG:Ce. A particular advantage of LuAG:Ce is its higher density resulting in thinner screens with higher spatial resolution. The material is mechanically and chemically stable, and can be machined into a variety of shapes and sizes including prisms, spheres and very thin plates.

Advantages:

• high density
• fast decay time
• wavelength of luminescence emission well suited for photodiode and avalanche diode readout
• chemical and mechanical resistance
• very good machining property
• temperature resistance

Main usage:

• PET scanners
• high energy gamma and charged particle detection
• high spatial resolution imaging screens for gamma, X, beta and UV rays

For more information see Technical parametrs (.pdf) 

Very thin Imaging Screens 

Crytur has developed very thin YAG:Ce and LuAG:Ce screens, down to thickness of 5 µm optically coupled to FOP (Fiber Optic Plate) or a glass base. Screens are designed to be used for electron, X-Ray or UV (Ultra Violet light) imaging. Glue thickness is less then 1 µm. On request, special diffuse bonding technology (without glue) can be applied for small diameters.

Optional: Al, ITO or C (Aluminum, Indium Tin Oxide or Carbon) conductive and reflection layers can be applied on the entrance side; optional AR coating on the light output side.

Optional: optical coupling of theYAG:Ce/FOP image detector to customer’s CCD image sensor.

For more information see Products section - Imaging systems or X-ray cameras.