BragGrate™- Bandpass Filter

Reflecting Bragg Grating (RBG) for spectral filtering

BragGrate™ Bandpass Filter is a reflecting Bragg grating (RBG) recorded in a bulk of photosensitive silicate glass. The filters are used to clean up laser spectral noise with a bandwidth as narrow as 50 pm in visible and near IR regions. In Raman spectroscopy applications, combining the bandpass filters with matching BragGrate™ Notch Filters enables Raman shift measurements down to 5 cm^-1 from the laser line. BragGrate™ filters have superior environmental stability and can handle high power optical radiation.

785 nm laser diode ASE background clean up with a BragGrate™ Bandpass filter with bandwidth <7 cm-1

Specifications

• Diffraction Efficiency (DE): >90%
• Spectral Bandwidth: 50 pm to 0.5 nm
• Operating Range λ: 350-2700 nm
• Grating Thickness: 0.5-15 mm
• Apertures: 1-10 mm²
• Deflection Angles: 5-90 deg

Standard Parameters

• Center Wavelength: 405, 488, 514, 532, 633, 785, 1064 nm
• Spectral Bandwidth (FWHM): <7 cm^-1
• Diffraction Efficiency: >90%
• Lateral Dimensions: 5×5 mm²
• Deflection Angle: 20 deg

Advantages & Features

Schematics of a possible RBG Bandpass filter configuration

• High spectral selectivity
• Superior environmental stability, no degradation over lifetime
• High powered operations over 1 kW
• High average power operation >20 W
• High energy operations up to 5 J/cm²
• No polarization dependence
• Near-diffraction-limited beam quality

Applications

• Spectral filtering and noise cleaning of laser beams
• ASE filters for Raman laser diode sources
• Spectral detection

• Tunable filters for high resolution spectroscopy