BragGrate™ Mirror

Reflecting Bragg Grating (RBG) for laser mode selection / diode laser wavelength locking

The BragGrate™ Mirror is a reflecting volume Bragg grating recorded in a bulk of photosensitive silicate glass. BragGrate™ Mirrors are placed in a laser resonator which enables spectral and thermal management of the laser radiation.  The laser modal structure is controlled by the longitudinal mode selection with the bandwidth down to 10 GHz and the customized central wavelengths with accuracy of 0.1-0.5 nm. BragGrate™ Mirrors have a record low absorption and scattering that allows them to withstand record high optical densities of up to 10 J/cm². This also yields a thermal laser wavelength shift reduction of up to 5 pm/K at 532 nm.

Schematics of LD bar stabilization with a BragGrate™ Mirror.

Specifications

• Diffraction Efficiency (DE): 3-99.7%
• Spectral Bandwidth: 20 pm to 20 nm
• Wavelength Range: 320-2700 nm
• Grating Thickness: 0.50-20 mm
• Apertures: up to 35×35 mm²
• Angular Selectivity: 1-100 mrad
• Incident/Output Angles: 0-45 deg
• Grating to Surface Tilt Angle: 0-10 deg
• Absorption/Scattering Losses: <2%

Standard Parameters

• Center Wavelength: 405, 78X, 8XX, 9XX, 10XX, 15XX, 19XX nm
• Spectral Bandwidth: (FWHM): 0.1-0.3 nm
• Diffraction Efficiency: 10-35, 90, 99 %
• Lateral Dimensions: 1.5×2, 1.5×12, 5×5 mm²
• Thickness: 1, 2.5, 4.0 mm

Normalized spectra of 2W free running LD and with BragGrate™ Mirror at different T. The narrowed linewidth was < 45 pm. Insert: mode profile with a 10% DE BragGrate™ Mirror

Advantages & Features

• High power operations, over 1 kW
• High energy operations up to 5 J/cm²
• Low to No power penalty
• Unrestricted lifetime; no degradation of parameters has been detected for 10 years
• Narrowing of laser line down to 20 pm with superior thermal stability
• Environmental stability
• No polarization dependence
• Unique solutions to achieve SFM oscillations
• Nearly diffraction-limited beam quality

Applications

• Longitudinal and transverse mode selection in laser resonators
• Solid-state lasers
• High powered laser diodes
  
• MM and SM laser diode modules for spectroscopy
• Narrow line spectroscopic laser sources (e.g. Raman)
  
• Fiber Lasers
  
• Laser radars, LIDARS, etc…