|
Transparency Range
|
160-2600nm
|
|
SHG Phase Matchable
Range
|
551 ~ 2600nm (Type
I)
790-2150nm (Type II)
|
|
Therm-optic Coefficient
(°C, λ in μm)
|
dnx/dT=-9.3X10-6
dny/dT=-13.6X10-6
dnz/dT=(-6.3-2.1λ)X10-6
|
|
Absorption Coefficient
|
<0.1%/cm at 1064nm
<0.3%/cm at 532nm
|
|
Angle Acceptance
|
6.54mrad-cm
(φ, Type I,1064 SHG)
15.27mrad-cm
(q, Type II,1064 SHG)
|
|
Temperature Acceptance
|
4.7°C-cm
(Type I, 1064 SHG)
7.5°C-cm (Type
II,1064 SHG)
|
|
Spectral Acceptance
|
1.0nm-cm (Type I, 1064
SHG)
1.3nm-cm (Type II,1064 SHG)
|
|
Walk-off Angle
|
0.60° (Type I 1064
SHG)
0.12° (Type II 1064 SHG)
|
|
NLO Coefficients
|
deff(I)=d32cosΦ (Type
I in XY plane)
deff(I)=d31cos2θ+d32sin2θ
(Type I in XZ plane)
deff(II)=d31cosθ
(Type II in YZ plane)
deff(II)=d31cos2θ+d32sin2θ
(Type II in XZ plane)
|
|
Non-vanished NLO
susceptibilities
|
d31=1.05 ±
0.09 pm/V
d32= -0.98 ± 0.09
pm/V
d33=0.05 ± 0.006 pm/V
|
|
Sellmeier Equations(λ in μm)
|
nx2=2.454140+0.011249/(λ2-0.011350)-0.014591λ2-6.60x10-5λ4
ny2=2.539070+0.012711/(λ2-0.012523)-0.018540λ2+2.0x10-4λ4
nz2=2.586179+0.013099/(λ2-0.011893)-0.017968λ2-2.26x10-4λ4
|
SHG conversion
efficiencies of more than 70% for pulse and 30% for cw Nd:YAG
lasers, and THG conversion efficiency over 60% for pulse Nd:YAG
laser have been observed by using VLIN’s LBO crystal.
LBO's applications
* More than 480mW output
at 395nm is generated by frequency doubling a 2W mode-locked
Ti:Sapphire laser (<2ps, 82MHz). The wavelength range of
700-900nm is covered by a 5x3x8mm3 LBO crystal.
* Over 80W green output is obtained by SHG of a Q-switched
Nd:YAG laser in a type II 18mm long LBO crystal.
* The frequency doubling of a diode pumped Nd:YLF laser (>500µJ
@ 1047nm, <7ns, 0-10KHz) reaches over 40% conversion efficiency
in a 9mm long LBO crystal.
* The VUV output at 187.7 nm is obtained by sum-frequency
generation.
* 2mJ/pulse diffraction-limited beam at 355nm is obtained by
intra-cavity frequency tripling a Q-switched Nd:YAG laser.
LBO's Non-Critical
Phase-Matching
|
Table 3. Properties of
type I NCPM SHG at 1064nm
|
|
NCPM Temperature
Acceptance Angle
Walk-off Angle
Temperature Bandwidth
Effective SHG Coefficient
|
148°C
52 mrad-cm1/2
0
4°C-cm
2.69 d36(KDP)
|
AS shown in table 3,
Non-Critical Phase-Matching (NCPM) of LBO is featured by no
walk-off, very wide acceptance angle and maximum effective
coefficient. It promotes LBO to work in its optimal condition.
SHG conversion efficiencies of more than 70% for pulse and 30%
for cw Nd:YAG lasers have been obtained, with good output
stability and beam quality.
As shown in Fig.3, type I
and type II non-critical phase-matching can be reached along
x-axis and z-axis at room temperature, respectively.
LBO's applications
* By using LBO
crystal,over 11W of average power at 532nm was obtained by
extra-cavity SHG of a 25W Antares mode-locked Nd:YAG laser
(76MHz, 80ps).
* By using LBO crystal,20W
green output was generated by frequency doubling a medical,
multi-mode Q-switched Nd:YAG laser. Much higher green output is
expected with higher input.
LBO’s OPO and OPA
LBO is an excellent NLO
crystal for OPOs and OPAs with a widely tunable wavelength range
and high powers. These OPO and OPA that are pumped by the SHG
and THG of Nd:YAG laser and XeCl excimer laser at 308nm have
been reported. The unique properties of type I and type II phase
matching as well as the NCPM leave a big room in the research
and applications of LBO’s OPO and OPA. Fig.4 shows the
calculated type I OPO tuning curves of LBO pumped by the SHG,
THG and 4HG of Nd:YAG laser in XY plane at the room temperature.
And Fig. 5 illustrates type II OPO tuning curves of LBO pumped
by the SHG and THG of Nd:YAG laser in XZ plane.
LBO's applications
* A quite high overall conversion efficiency and 540-1030nm
tunable wavelength range were obtained with OPO pumped at 355nm.
* Type I OPA pumped at 355nm with the pump-to-signal energy
conversion efficiency of 30% has been reported.
* Type II NCPM OPO pumped by a XeCl excimer laser at 308nm has
achieved 16.5% conversion efficiency, and moderate tunable
wavelength ranges can be obtained with different pumping sources
and temperature tuning.
* By using the NCPM technique, type I OPA pumped by the SHG of a
Nd:YAG laser at 532nm was also observed to cover a wide tunable
range from 750nm to 1800nm by temperature tuning from 106.5°C to
148.5°C.
* By using type II NCPM LBO as an optical parametric generator
(OPG) and type I critical phase-matched BBO as an OPA, a narrow
linewidth (0.15nm) and high pump-to-signal energy conversion
efficiency (32.7%) were obtained when it is pumped by a 4.8mJ,
30ps laser at 354.7nm. Wavelength tuning range from 482.6nm to
415.9nm was covered by increasing the temperature of LBO or
rotating BBO.
LBO’s Spectral NCPM
Not only the ordinary
non-critical phase matching (NCPM) for angular variation but
also the noncritical phase matching for spectral variation
(SNCPM) can be achieved in the LBO crystal. As shown in Fig.2,
the phase matching retracing positions are λ1=1.31μm
with θ =86.4°, φ=0° for Type I and λ2=1.30μm with
θ=4.8°, φ=0° for Type II. The phase matching at these positions
possess very large spectral acceptances Δλ. The calculated Δλ at
λ1 and λ2are 57nm-cm-1/2 and
74nm-cm-1/2 respectively, which are much larger than
the other NLO crystals. These spectral characteristics are very
suitable for doubling broadband coherent radiations near 1.3μm,
such as those from some diode lasers, and some OPA/OPO output
without linewidth-narrowing components.
AR-coatings of LBO
VLIN provides LBO crystal
with the following AR-coatings:
* Dual Band AR-coating (DBAR) of LBO for SHG of 1064nm.
· low reflectance (R<0.2% at 1064nm and R<0.5% at 532nm );
· high damage threshold (>500MW/cm2at both
wavelengths);
· long durability.
* Broad Band AR-coating (BBAR) of LBO for SHG of tunable lasers.
* Other coatings are available upon request.
VLIN Warranty on LBO
Specifications
* Dimension tolerance: (W±0.1mm)x(H±0.1mm)x(L+0.5/-0.1mm)
(L≥2.5mm)
(W±0.1mm)x(H±0.1mm)x(L+0.1/-0.1mm)
(L<2.5mm)
* Clear aperture: central 90% of the diameter
* No visible scattering paths or centers when inspected by a
50mW green laser
* Flatness: less than λ/8 @ 633nm
* Transmitting wavefront distortion: less than λ/8 @ 633nm
* Chamfer:
≤0.2mmx45°
* Chip: ≤0.1mm
* Scratch/Dig code: better than 10/ 5 to
MIL-PRF-13830B
* Parallelism: better than 20 arc seconds
* Perpendicularity: ≤5 arc minutes
* Angle tolerance: Δθ≤0.25°, ΔΦ≤0.25°
* Damage threshold[GW/cm2 ]: >10 for 1064nm, TEM00,
10ns, 10HZ (polished only)
>1 for 1064nm, TEM00, 10ns, 10HZ (AR-coated)
>0.5 for 532nm, TEM00, 10ns, 10HZ (AR-coated)
* Quality Warranty Period: one year under proper use.
NOTES
1. LBO has a
very low susceptibility to moisture. Users are advised to
provide dry conditions for both the use and preservation of
LBO.
2. Polished surfaces of LBO requires precautions to prevent any
damage.
3. VLIN engineers can select and design the best LBO crystal for
you, if the main parameters of your laser are provided, such as
energy per pulse, pulse width and repetition rate for a pulsed
laser, power for a cw laser, laser beam diameter, mode
condition, divergence, wavelength tuning range, etc.
