A single-longitudinal-mode laser is one whose output beam satisfies both single-longitudinal-mode and single-transverse-mode conditions. Single-longitudinal-mode means that only a single longitudinal mode (i.e., a single frequency) oscillates within the laser cavity. This results in an extremely narrow output linewidth, providing excellent monochromaticity and coherence, which is crucial for applications such as precision spectroscopy and interferometry. Single-transverse-mode (also known as the fundamental transverse mode, TEM₀₀) refers to a beam whose intensity profile exhibits a perfect Gaussian distribution in the transverse plane. This mode features a small divergence angle, a circular beam spot, and can be focused by a lens to the diffraction limit, offering optimal beam quality and directionality. The combination of these two properties ensures high purity and stability in both the temporal and spatial domains. LBTEK offers a comprehensive product line of single-longitudinal-mode lasers. In addition to free-space output models, we also provide fiber-coupled single-longitudinal-mode lasers, which deliver laser output via an optical fiber pigtail. This design greatly facilitates system integration and optical alignment, while the waveguide properties of the fiber help maintain beam quality and mode stability. LBTEK's single-longitudinal-mode lasers cover center wavelengths from 473 nm to 1064 nm, featuring narrow linewidth, high power stability, excellent coherence, superior monochromaticity, and good temperature stability. They are widely applicable in fields such as DNA sequencing, digital imaging, optical communications, precision ranging, gravitational wave detection, and nonlinear optics research. Important Note: Customization and Service LBTEK provides laser customization services and can tailor specific parameters, such as wavelength, according to requirements. For fiber-coupled lasers, fiber connectors with different numerical apertures and core diameters are also available as options. Please note that the single-longitudinal-mode lasers offered by LBTEK are standard models with fixed output power and do not support user-adjustable power. For special customization needs, please contact LBTEK Technical Support. Safety Warning Laser use involves potential risks. Even at very low power, laser beams can cause permanent eye damage. Always adhere to all safety guidelines, wear protective goggles specifically designed for the laser wavelength during operation, and ensure the beam path is kept away from eyes.