GaSe Crystals
Simple description：
GaSe crystal, also known as gallium selenide crystal, is an inorganic semiconductor compound composed of gallium and selenium. It exhibits a dark brown luster, possesses a layered structure, and is an important nonlinear optical material.
Advantages：Excellent nonlinear optical performance, High damage threshold, Wide transparency range, Strong terahertz oscillation performance
Application fields：Laser technology, Terahertz technology, Optical components, Optoelectronics
Simple description：
GaSe crystal, also known as gallium selenide crystal, is an inorganic semiconductor compound composed of gallium and selenium. It exhibits a dark brown luster, possesses a layered structure, and is an important nonlinear optical material.
Detailed description：
GaSe crystals have a hexagonal crystal system structure with a space group of 62m. This structural feature results GaSe crystals being composed of alternating layers of closely packed two-dimensional selenium atoms and gallium atoms, with each layer interconnected by relatively weak van der Waals forces At room temperature (300K), the bandgap of GaSe crystals is approximately 2.2 electron volts (eV), exhibiting characteristics of a wide bandgap semiconductor. Additionally, GaSe crystals possess significant nonlinear optical properties, with a large nonlinear coefficient (about 54 picometers per volt, pm) and a high damage threshold. Their transmission wavelength range is between 0.65 and 18 micrometers, with an ultra-low absorption coefficient allowing them to effectively transmit light within this wavelength range and minimize energy loss.
Advantages：
1. Excellent nonlinear optical performance: GaSe crystals have a large nonlinear coefficient, which allows them to effectively produce nonlinear optical, such as second harmonic generation (SHG) and difference frequency generation (DFG), under high-intensity laser irradiation.
2. High damage threshold:Se crystals can maintain stable operation under high-power laser conditions and are unlikely to fail due to optical damage.
3. Wide transparency range: GaSe crystals have a transparency range, especially in the mid-infrared broadband electromagnetic wave region, where their ultra-low absorption coefficient allows them to effectively transmit light in this wavelength range.
4. Strong terahertz oscillation performance: Due to their excellent nonlinear optical performance and wide spectral transparency, GaSe crystals are used in the generation and detection ofahertz waves, particularly suitable for broadband terahertz oscillation and detection using laser sources with pulse widths below 20 femtoseconds.
Application fields：
1. Laser technology: GaSe crystals can be used for second harmonic generation in CO2 lasers, converting CO2 laser to the visible or near-infrared spectrum. Meanwhile, it can also be used for optical mixing in the mid-infrared region and the generation of different frequencies.
2. Terahertz technology: GaSe crystals have significant applications in the generation and detection of terahertz waves. By adjusting the thickness of the GaSe crystal selective control of the THz wave frequency can be achieved.
3. Optical components: GaSe crystals can be used to manufacture various optical components, such as lenses windows, and prisms, for use in infrared imaging, infrared sensors, and other devices.
4. Optoelectronics: GaSe crystals also have potential in the field of optoelectronics, such as the manufacture of infrared fibers and optical waveguide devices.
Parameter：
| Parameter | Value |
| Chemical formula | GaSe |
| Crystal system | hexagonal crystal system |
| Space point group | 62m |
| Density | 5.03g/cm³ |
| Specific heat | 960±10℃ |
| Band gap | 2.2eV |
| Nonlinear coefficient | 54pm/V |
| Transmission band | 0.65-20μm |
| Absorption coefficient | Ultra-low |
