Ultrathin LBO for Ultrafast Lasers

For frequency conversions of ultrafast lasers, one of the the main concerns is pulse broadening induced by group velocity (Vg) mismatch between the input pulse(s) and the generated pulse in an NLO crystal. In order to avoid pulse broadening, the thickness of the crystal should not exceed the maximum length (Lmax) as defined by the pulsewidth divided by the inversed group velocity mismatch (IGVM = ΔVg-1). The table below lists the Lmax for second harmonic generation (SHG) and sum frequency generation (SFG) of 10 fs pulses at the wavelength range of a Ti:Sapphire laser, the most popular ultrafast laser.

Type I PM on XY plane	SHG @ 700 nm	SHG @ 800 nm	SHG @ 900 nm	SHG @ 1064 nm	SFG @ 800nm + 400nm	SFG @ 900 nm + 450nm
IGVM (ps/cm)	1.73	1.20	0.87	0.43	4.47	3.33
Lmax@10fs (µm)	60	85	115	232	22	30

Apparently a thickness of sub-100 µm ( 0.1 mm) is desired. In particular, crystals as thin as 10-20 µm may be needed for reaching shorter wavelengths.

Newlight Photonics Inc. can provide LBO crystals as thin as 10 µm (0.01 mm) for frequency conversion of ultrafast pulses.

We also supply birefringent calcite plates and alpha-BBO plates for compensation of temporal walkoff in nonlinear crystals (time delay compensators), please contact us for details.

Standard Products

Part No.	width x height x thickness	Coating	Application
LTC2511	5 x 5 x 0.01 mm	uncoated	SHG @ 800 nm
LTC2512	5 x 5 x 0.02 mm	uncoated	SHG @ 800 nm
LTC2513	5 x 5 x 0.03 mm	AR@800/400nm or uncoated	SHG @ 800 nm
LTC2515	5 x 5 x 0.05 mm	AR@800/400nm or uncoated	SHG @ 800 nm
LTC2521	5 x 5 x 0.1 mm	AR@800/400nm or uncoated	SHG @ 800 nm
LTC2525	5 x 5 x 0.5 mm	AR@800/400nm or uncoated	SHG @ 800 nm
LTC2531	5 x 5 x 1.0 mm	AR@800/400nm or uncoated	SHG @ 800 nm
LTC2532	5 x 5 x 2.0 mm	AR@800/400nm or uncoated	SHG @ 800 nm
LTC3511	5 x 5 x 0.01 mm	uncoated	SFG @ 800nm + 400nm
LTC3512	5 x 5 x 0.02 mm	uncoated	SFG @ 800nm + 400nm
LTC3513	5 x 5 x 0.03 mm	AR@800/400/267nm or uncoated	SFG @ 800nm + 400nm
LTC3515	5 x 5 x 0.05 mm	AR@800/400/267nm or uncoated	SFG @ 800nm + 400nm
LTC3521	5 x 5 x 0.1 mm	AR@800/400/267nm or uncoated	SFG @ 800nm + 400nm
LTC3525	5 x 5 x 0.5 mm	AR@800/400/267nm or uncoated	SFG @ 800nm + 400nm
LTC3531	5 x 5 x 1.0 mm	AR@800/400/267nm or uncoated	SFG @ 800nm + 400nm
LTC3532	5 x 5 x 2.0 mm	AR@800/400/267nm or uncoated	SFG @ 800nm + 400nm

Coating

We provide AR coatings @ 800nm and its harmonics. Please specify your requirements if coatings at the other wavelengths are needed.

Substrate

Crystals of thickness less than 50 µm are supplied optically contacted on UV fused silica substrates with a typical thickness of 2 mm. The ultrafast pulses should be incident on the crystal side.

Mount

For customer convenience and protection of ultrathin crystals, all ultrathin crystals are pre-mounted on a 1" ( 25.4 mm ) anodized aluminum (Al) holder. A standard 1" mirror mount may be conveniently used to tune the crystals for optimized frequency conversions.
( Mirror mount and post are not included)

Specifications on finished ultrathin LBO

Wavefront distortion	less than λ/8 @ 633 nm
Clear aperture	> 90% central area
Flatness	λ/8 @ 633 nm
Surface quality	10/5 Scratch/Dig per MIL-O-13830A
Parallelism	better than 20 arc seconds
Perpendicularity	15 arc minutes
Angle tolerance	Δθ < +/-0.25o, Δφ < +/-0.25o