Single Frequency Laser Selection Guide

• Wavelength. Match the laser wavelength to the measurement band, detector response, sample absorption and fluorescence background. See the laser wavelength table for the complete UV, visible and infrared list.
• Longitudinal mode. Use a single longitudinal mode laser when the instrument requires narrow spectrum linewidth, long coherence length, low phase noise or stable interference fringe contrast.
• Output power. Select the minimum useful laser power for the application. Higher power may increase signal, but can also increase sample heating, fluorescence background and optical safety requirements.
• Beam quality. TEM00 mode and low M2 are important for Raman spectroscopy, holography, interferometry, fluorescence excitation, microscopy and fiber coupling.
• Stability and noise. Ultra-stable power option and low amplitude noise should be selected when the detector integrates weak signals or compares small intensity changes.
• Optical feedback. Instruments with lenses, fibers, cells or reflective samples may need an optical isolator to protect the laser from back reflection.

Longitudinal mode             Single longitudinal mode (SLM)
Spectrum linewidth            Narrow linewidth; model dependent
Coherence length              Long coherence length; model dependent
Transverse mode               TEM00, low M2
Polarization                  Linear polarization options available
Power stability               Standard and ultra-stable options
Noise                         Low amplitude noise options
Output format                 Free-space or fiber-coupled options
Operating format              CW; selected wavelengths also available Q-switched

• For Raman systems, select the wavelength after considering Raman signal strength, fluorescence background, sample absorption and detector sensitivity. See the Raman laser selection guide.
• For interferometry and holography, verify the required coherence length and phase-noise tolerance before choosing wavelength and output power.
• For compact OEM instruments, confirm the laser-head size, heat load, power supply format and modulation requirement from the product data sheet.
• For special wavelength, higher output power, fiber coupling or ultra-stable operation, use the Information Request Form and include the target wavelength, power, beam size, stability and application.