Nonlinear crystal technologies

Photo of nonlinear optical crystals
Applying innovative techniques to create high-quality optical crystals

BAE Systems produces crystals and other materials for use primarily in shifting the wavelength and frequency of laser light. We work with government research organizations, academia, and industry, both in the U.S. and internationally, to develop high-quality crystals for use in optical systems. Applications include infrared countermeasures, threat detection and targeting systems, sensor protection, infrared spectrometry, laser surgery, coherent x-ray generation, and high-power, directed-energy lasers.

Production capabilities

For more than 25 years we have refined specialized development processes in our world-class, 3,000-square-foot, bulk crystal growth facility and III-V semiconductor epitaxial growth facilities. We specialize in the following research and development areas:

Infrared optical materials

Design, produce, and characterize optical materials for operation in the infrared, enabling diverse applications ranging from basic science research to the next generation of military optical systems.

Nonlinear optical (NLO) crystals

Develop unique, world class mid-infrared NLO crystals exhibiting high gain, broad wavelength coverage, and scalability to high energies and average powers to enable new laser applications.

Crystal growth process development

Leverage a deep understanding of materials science to develop growth and fabrication processes that reliably produce high-quality crystals.

Available NLO crystals

In addition to the established NLO materials described here, we develop custom crystals to meet unique customer needs.

Zinc Germanium Phosphide (ZGP, ZnGeP2)

Photo of Zinc Germanium Phosphide crystal

The nonlinear optical crystal of choice for high-energy and high-power laser frequency conversion in the 2- to 8-μm spectral range. This is the most mature crystal technology in production at BAE Systems (>25 years). Our proprietary processing offers the lowest losses, largest bulk sizes, and highest laser damage thresholds of any commercial source.

Cadmium Silicon Phosphide (CSP, CdSiP2)

Photo of Cadmium Silicon Phosphide crystal

A new nonlinear optical crystal for laser frequency conversion in the 1- to 8-μm spectral range. The material is particularly promising due to its high nonlinear coefficient of 84.5 pm/V, which is the largest for any new phase-matchable inorganic crystal in four decades.

Orientation Patterned Gallium Arsenide (OP-GaAs)

Photo of OP-GaAs crystal

A quasi-phase-matched alternative for the mid-infrared. The crystal offers superior performance for continuous wave and fiber laser pumping.

Orientation Patterned Gallium Phosphide (OP-GaP)

Photo of OP-GaP crystal

A new quasi-phase-matched semiconductor. The material enables widely-available 1-μm and 1.5-μm lasers to be frequency-shifted deep into the mid-infrared at a dramatically higher gain than QPM oxides.

Comparison of crystals

Property ZGP CSP OP-GaAs OPGaP
Nonlinear coefficient, dij [pm/V] 75 84.5 94 70
Transparency range [μm] 0.72-12 0.50-9 0.5-12 0.57-12
Thermal conductivity [w/mK] 35 14 55 110
Laser damage threshold [J/cm2] ~3 ~3 ~3 ~5
Knoop hardness [kg/mm2] 980 930 750 850

Other materials

In addition other, exotic crystals have been produced at BAE Systems, including:

Cadmium Germanium Arsenide (CGA, CdGeAs2): Exhibits the highest nonlinear coefficient (236 pm/V) among known compounds.

Silver Gallium Selenide (AgSe, AgGaSe2): Available from other suppliers but increasingly difficult to purchase, BAE Systems produced devices > 40-mm-long with record performance for frequency-doubling CO2 lasers.

Quarternary thio- and seleno-gallates: AgGaGeS4 and AgGaGe5Se12 crystals have been grown at BAE Systems as lower-gain alternatives for 1-μm laser pumping.

Gallium Selenide (GaSe): Available from other suppliers, this extremely soft and micaceous crystal has a high nonlinearity, broad IR transparency, and very large birefringence. BAE Systems has successfully produced Wollaston prisms using this material.

Mixed ternary III-V semiconductors: Using our unique Hydride Vapor Phase Epitaxy (HVPE) facility, BAE Systems can produce bulk wafers of InGaAs, InGaP, InAsP, and GaInAsP with thicknesses = 1mm for applications requiring lattice constant or band-gap engineering.

Place an order

Before you order: Identify the best NLO crystal for your application using this free crystal selection software from AS-Photonics.

To order: For detailed technical information or to request a quote, contact us at