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GaSe Crystal

POC-OC-122510-GaSe Crystal

  • Transparency range: 0.65 µm to 18 µm
  • High nonlinearity and birefringence
  • Soft and cleaves along the [001] plane
  • Not suitable for cutting and polishing at certain angles
  • Delivered uncoated and mounted for safe handling

Customizable Components Available for This Material to Meet Your Specific Needs!

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GaSe Crystal Material General Description

Gallium Selenide (GaSe) crystals are unique negative uniaxial semiconductor crystals with hexagonal symmetry, featuring a bandgap of 2.2 eV at 300 K. These crystals offer exceptional damage thresholds and large nonlinear coefficients, with a broad transparency range from 0.62 µm to 20 µm. GaSe crystals exhibit low absorption coefficients, making them highly suitable for mid-IR applications, terahertz wave generation, and detection systems. Their strong birefringence enhances their application versatility in high-frequency terahertz spectrometry and imaging systems. However, their fragile structure limits the feasibility of antireflection coatings.

GaSe Crystal General Applications

GaSe crystals are widely used in advanced photonics applications:

  • Mid-IR Difference Frequency Generation (DFG): Useful in generating long-wave infrared signals, leveraging high nonlinear coefficients.
  • Second Harmonic Generation (SHG): Efficient in CO2 and dye laser frequency doubling.
  • Terahertz Generation: Suitable for generating terahertz waves via optical rectification.
  • Terahertz Detection: Integrated into THz time-domain spectroscopy (THz-TDS) systems for precise spectrometric analyses.
  • Advanced Research: Applied in terahertz imaging systems, atmospheric gas sensing, and nonlinear optical experiments.

Chemical and Structural Properties

Property

Value

Chemical Formula

GaSe

Crystal Structure

Hexagonal, -62m symmetry

Lattice Parameters

a = 3.74 Å, c = 15.89 Å

Density

5.03 g/cm³

Mohs Hardness

Approx. 0

Transparency Range

0.62–20 µm

Nonlinear Coefficient (d22)

54 pm/V

Refractive Indices (nₒ, nₑ)

nₒ > nₑ (varies with wavelength)

Sellmeier Equations

Specified for 5.3 µm and 10.6 µm

Damage Threshold

28 MW/cm² (9.3 µm, 150 ns pulse)

Optical, Laser and Nonlinear Optical Properties

Wavelength (µm)

nₒ

nₑ

Walk-Off Angle

5.3

2.7233

2.3966

4.1°

10.6

2.6975

2.3745

–

Standard Fabrication Specifications

Parameter

Value

Standard Sizes

≥ Ø7 mm clear aperture

Surface Quality

Cleaved surface

Thickness Tolerance

±0.2 mm

Mount Options

Ø25.4 mm anodized aluminum mount

Spectrum Transmission Curve:

The spectral transmission curve of GaSe demonstrates minimal absorption across the 0.62 µm to 20 µm range, making it highly effective for mid-infrared applications.

Coating Specification:

 

  • Coatings: Unavailable due to the fragile nature of GaSe.
  • Surface Finish: Cleaved for maximum performance.
  • Adhesion Test Compliant with MIL-C-675C military standards, an adhesion test involved applying a tape that meets LT-90 specifications onto the lens film layer. The tape was affixed fully and then removed vertically. This procedure was performed three times, resulting in no blistering or peeling.
  • Temperature Test In line with MIL-C-675C specifications, test pieces were subjected to temperatures of -62±1℃ and 71±1℃. After maintaining them at room temperature (16℃~32℃) for two hours, the adhesion test was repeated, confirming no film detachment.
  • Abrasion Resistance Test Conforming to MIL-C-675C and CCC-C-440 standards, the abrasion resistance test involved a gauze tester applying a minimum force of 1.0 lbs (0.45 kg) to the film. This was repeated 25 times with gauze widths of 1/4 inch (6.4mm) and 3/8 inch (9.5mm), ensuring no damage occurred to the film surface.
  • Humidity Test Under MIL-C-675C criteria, the test piece was placed in a controlled temperature and humidity chamber set to 49 ±2℃ and 95%~100% humidity for 24 hours. The film remained intact, with no peeling, scratches, or other defects.
  • Solvent and Cleaning Testing Following MIL-C-675C specifications, test pieces were exposed to room temperature conditions (16℃~32℃) and tested with acetone and alcohol for at least 10 minutes each. After air drying and subsequent cleaning with a cotton cloth soaked in alcohol, the film surface showed no signs of peeling or scratches.
  • Salt Spray Test After 100 hours in a 35°C environment with a 5% saltwater concentration, the film showed no signs of damage.

POC Strength and Capabilities

 

Photonics On Crystals (POC) specializes in providing high-quality GaSe crystals optimized for nonlinear optical and terahertz applications. With precise fabrication capabilities, POC offers customizable dimensions and ensures superior quality assurance for fragile crystal materials. Their expertise guarantees reliable solutions tailored for advanced photonics research.

Standard Products

Clear Aperture

Length

Orientation

Coating

Price (USD)

≥ Ø7 mm

0.2 mm

Z-cut

Uncoated

$1,950

≥ Ø7 mm

0.5 mm

Z-cut

Uncoated

$1,750

≥ Ø7 mm

1.0 mm

Z-cut

Uncoated

$2,150

≥ Ø7 mm

2.0 mm

Z-cut

Uncoated

$2,450

POC-OC-122510-GaSe Crystal

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