BragGrate™ Mirror

Reflecting Bragg Grating (RBG) for laser mode selection

The BragGrate™ Mirror is a reflecting volume Bragg grating (RBG) recorded in a bulk of photosensitive silicate glass. BragGrate™ Mirror placed in a laser resonator enables spectral and thermal management of the laser radiation and can withstand high optical densities up to 5 J/cm2. The laser modal structure is controlled by the longitudinal mode selection with the bandwidth down to 20 pm and the customized central wavelengths with accuracy of 0.1-0.5 nm. BragGrate™ Mirrors have record low absorption and allow thermal laser wavelength shift reduction to 0.005 nm/K.

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 mm
• Angular Selectivity: 1-100 mrad
• Incident/Output Angles: 0-45 deg
• Grating to Surface Tilt Angle: 0-10 deg
• Absorption/Scattering Losses: <1%

Standard Parameters

• Center Wavelength: 405, 785, 976, 1064, 1532, 1908 nm
• Spectral Bandwidth: (FWHM): 0.2 nm
• Diffraction Efficiency: 10, 20, 50, 99 %
• Lateral Dimensions: 1.5×2, 1.5×12, 5×5 mm
• Thickness: 1, 2.5, 4.0 mm

Normalized spectra of 2W free running LD and with BragGrate™ Mirror feedback at different T. Linewidth of LD in external Bragg cavity was < 45 pm. Insert: reflected mode profile with a 10% DE BragGrate™ Mirror

Advantages & Features

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

Applications

• Solid-state lasers
• High powered laser diodes
  
• Narrow line spectroscopic laser sources (e.g. Raman)
  
• Narrow band output coupler
  
• Laser radars, LIDARS, etc…