KBBF Crystal KBBF es capaz de producir DUV e incluso luz coherente UV de vacío mediante la generación directa de un segundo armónico, pero un problema importante es su naturaleza de crecimiento en forma de placa que hace que sea muy difícil cultivar muestras de más de 4 mm de espesor a lo largo del eje c, y KBBF el cristal se escinde fácilmente, por lo que es imposible cortar el cristal a lo largo del ángulo de coincidencia de fase. Con una bomba de incidencia directa, el ángulo de incidencia externo aumentará a 90° para una longitud de onda del segundo armónico de 235 nm. Para resolver el problema… VENTAJAS 4ta generación armónica de láser Nd:YAG a 266nm (1) Ventajas de KBBF sobre BBO y CLBO ●Umbral de daño mucho más alto ●Absorción de dos fotones mucho más pequeña ●Sin efecto fotorrefractivo ●Sin humedad (2)Desventajas de KBBF sobre BBO y CLBO ● Deff (KBBF) = 1,53 (KDP) ● Deff (BBO) = 2,72 (KDP) ● Deff (CLBO) = 1,97 KDP) a 266 nm
Targets the KBBF can realize:
● Watt-level 193nm output power with 4th HG of Ti:sapphire Laser
● 100-500mw QCW 177.3nm output power with 6th HG of Nd:YAG Laser
● Wide tunable 2.0mw coherent light output from 220nm-175.0nm with 4th HG of tunable Ti:sapphire Laser
● average 7.8 watt-level 266nm output power
● stable mw-level 165-167nm output power
Optical Properties
Deff :
KBBF crystal belongs to the space group R32, so from the point group symmetry of D3 and the IEEE/ANSI standard definition of the dij coefficient, it has only two nonzero dij coefficients, namely, d11 and d14. The matrix form of the coefficients can be written as follows:
where d14 is very small according to both theoretical calculation and experiments. On the other hand, the effective deff coefficients of KBBF are:
deff=d11cosqcos3f (type I)
deff=d11cos2qsin3f (type = 2 * ROMAN II)
By comparing the fringe envelope of the d11 coefficient with the d36 coefficient in KDP, the d11 of KBBF is deduced to be (0.47+0.01) pm/V (d36(KDP)= 0.39 pm/V).
Transparency range ：
The cutoff wavelength on the UV side is located at 150 nm, and on the IR side around3.5mm. There is virtually no absorption in this region.
Sellmeier coefficients ：
Sellmeier equations as follows: (l is in units of mm)
no2=2.1738+0.00764λ2-0.01641-0.01174λ2
ne2=1.9319+0.00623λ2-0.00400-0.00356λ2
Damage threshold ：
It has been measured and compared with that of BBO under the same laser pump conditions (1064 nm, 1 Hz, 10.5 ns), The value is 35.51 J/cm2 (3.38 GW/ cm2) for the former, which is more than two times larger than the 13.47 J/cm2(1.28 GW/ cm2) of the latter; With a 200 fs pulse width and 1 kHz repetition rate at 390 nm, the damage threshold of KBBF was found to be as high as 60 GW/ cm2.
