RTP Crystals

What Are RTP Crystals?

Fig 1. Immersed RTP crystal grown by the TSSG method. [1]

RTP (rubidium titanyl phosphate, RbTiOPO₄) is a high-quality electro-optic and nonlinear optical crystal with properties similar to KTP (Potassium Titanyl Phosphate) but with distinct advantages. RTP offers strong second-order nonlinear coefficients, low photorefractive sensitivity, good thermal and mechanical stability, and a wide transparency window — making it well suited for frequency doubling (SHG), optical parametric oscillators (OPO), modulators, and other nonlinear devices across the visible to mid-infrared.

Compared to KTP, RTP offers higher optical damage resistance, lower piezoelectric ringing, and excellent thermal and mechanical stability, making it ideal for high-power and high-repetition-rate laser systems.

At Alfa Chemistry, we utilize advanced flux growth technology to produce high-quality RTP crystals that deliver reliable performance and exceptional electro-optic efficiency for demanding optical applications.

Features

• Large Electro-Optic Coefficients: r₃₃ = 35 pm/V, r₂₃ = 12.5 pm/V, enabling efficient light modulation with low driving voltages.
• High Laser Damage Threshold: >15 J/cm² (@1064 nm, 10 ns), suitable for high-power laser applications.
• Excellent Thermal Stability: Low thermal expansion and high thermal shock resistance.
• Wide Transparency Range: 350 nm - 4500 nm, covering UV to mid-infrared spectral regions.
• Resistance to Photorefractive Damage: Superior performance in high-power applications compared to many other electro-optic materials.
• Non-hygroscopic Nature: Maintains performance in various environmental conditions.
• High Optical Quality: Excellent homogeneity with minimal wavefront distortion.
• Low Photorefractive Effect: improved resistance to laser-induced refractive-index changes compared with some alternative crystals.

Specifications Product Options Applications

Product Name	RTP Crystals
Catalog No.	OPTIX-0009
Chemical Formula	RbTiOPO4
Crystal Structure	Orthorhombic, Point group mm2
Lattice Parameters	a = 12.96 Å, b = 10.56 Å, c = 6.49 Å
Density	3.6 g/cm3
Mohs Hardness	~5
Melting Point	~ 1000 °C
Transmission Wavefront Distortion	~810 °C
Angle Tolerance	△q < 0.5°, △f < 0.5°
Parallelism	20 arc sec
Perpendicularity	≤ 15 arc min
Surface Quality (Scratch/Dig)	20/10 to MIL-PRF-13830B
Flatness	λ/6 @633 nm
Hygroscopicity	No
Clear Aperture	> 90%
Coating	AR-coatings
Growing Orientation	Along Y-axis
Ferroelectric Transition Temperature	less than l/8 @ 633 nm dimension
Quality Warranty Period	One year under proper use
Nonlinear Optical Properties
NLO Coefficient	d31 = 2.0 pm/V, d32 = 3.6 pm/V, d33 = 8.3 pm/V, d24 = 3.6 pm/V, d15 = 2.0 pm/V
Damage Threshold	>15 J/cm² (@1064 nm, 10 ns, 10Hz)
Linear Optical Properties
Transparency Range	350nm - 4500nm
Extinction Ratio	> 20 dB @633 nm
Refractive Index	nx = 1.7673, ny = 1.7760, nz = 1.8574
Sellmeier Equations (λ in μm)	nx2=2.15559+0.93307[1-(0.20994/λ)2]-0.01452λ2 ny2=2.38494+0.73603[1-(0.23891/λ)2]-0.01583λ2 nz2=2.27723+1.11030[1-(0.23454/λ)2]-0.01995λ2
Thermal and Electrical Properties
Thermal Expansion Coefficients	a1=1.01×10-5, a2=1.37×10-5, a3=-4.17×10-6
Electrical Resistivity	1011-1012 ohm·cm
Static Half Wave Voltage @ 1064 nm	4 × 4 × 20 mm: 1,600 V 6 × 6 × 20 mm: 2,400 V 9 × 9 × 20 mm: 3,600 V
Ionic Conductivity	10-8 S/cm (room temperature, 10 kHz)
Electro-Optic Coefficients	r33=38.5pm/V (Y-cut), r33=35pm/V (X-cut) r23=12.5pm/V(Y-cut), r13=10.6pm/V (X-cut)
Thermo-Optical Coefficient	dλ/dT = - 0.029 nm /℃

Note: The data provided is for reference purposes. We recommend consulting with our technical team to verify suitability for your application.

RTP Crystal Product Options

• Standard Sizes (mm): 3×3×10, 4×4×10, 5×5×10, 10×10×10, and larger blanks up to custom sizes (e.g., 20×20×30 mm).
• Dimensions & Apertures: Precision-cut blanks or fully finished crystals.
• Shapes: Including but not limited to blanks, wafers, electro-optical switch components, etc.
• Crystal Orientation & Phase-Matching Cuts: Standard X/Y/Z and custom non-critical angle (NCPM) or temperature-tuned cuts for specific SHG/OPO wavelengths.
• AR Coatings: Single- or dual-wavelength, broadband, and high-damage coatings tailored to pump/SH/idler wavelengths.
• Polish & Surface Finish: Standard (10/5 scratch/dig typical), high-quality optical polish, or super-polish for high-finesse cavities.
• Flatness & Parallelism: Tighter tolerances for interferometric or resonant-cavity applications.

RTP crystals serve critical roles across multiple technologies:

Ler Q-Switching:

• High-repetition-rate Q-switches for Nd:YAG and other solid-state lasers
• Cavity dumping applications
• Laser pulse selection systems

Electro-Optic Modulation:

• Phase and amplitude modulators
• Optical switches and shutters
• Polarization controllers

High-Power Laser Systems:

• Industrial laser processing systems
• Medical laser equipment
• Scientific research lasers

Nonlinear Frequency Conversion:

• Second harmonic generation (SHG)
• Optical parametric oscillation (OPO)
• Sum and difference frequency generation

Aerospace:

• Laser ranging and targeting systems
• Optical communication systems
• Remote sensing equipment

Why Choose Our RTP Crystals?

• In-House Precision Fabrication: cutting, polishing, and coating under one roof for superior lead times and traceability.
• Wide Product Range & Fast Customization: from small research blanks to large OEM volumes and complex phase-matching cuts.
• Comprehensive Quality Testing: interferometric flatness, spectrophotometry, inclusion/scatter inspection, and optional laser-damage testing reports.
• Technical Support & Engineering Partnership: our applications team helps select crystal cut, coating, and mounting solutions to optimize conversion efficiency and lifetime.
• Supply Chain Reliability & Documentation: ISO-quality practices, batch traceability, and export documentation for global customers.

Reference

1. Tseitlin, M., et al. Journal of crystal growth 310.7-9 (2008): 1929-1933.