BragGrate™ Notch Filter

Narrow-Line Notch Filter for Ultra Low-Frequency Raman Spectroscopy

Extend your Raman system into the THz frequency range (5-200 cm^-1)

Click here to download presentation with BragGrate™ Raman Filter results

BragGrate™ Notch Filter

BragGrate™ Notch Filter (BNF) is a reflective volume Bragg grating recorded in a bulk of photosensitive silicate glass. Ultra-Narrow-Band Notch Filters reflect light with bandwidths as narrow as 5 cm^-1 while all other wavelength pass unaffected with up to 95% total transmission. BNF’s enable simultaneous measurements of Stokes and Anti-Stokes Raman bands down to 5 cm^-1 with a single stage spectrometer. Our Notch filters can withhold temperatures of up to 400°C and are fully environmentally stable with a practically unlimited
life-time. Central wavelengths of the filters can be
angle tuned by several nanometers without reduction
of the filter optical density.

Ultra-low frequency Raman spectrum of SiGe superlattice at 532 nm with LabRAM HR Evolution and BragGrate Notch Filters (Courtesy of P.H. Tan, Institute of Semiconductors, CAS, Beijing, P.R. China)

Specifications

• Achievable attenuation: > 99.99% (OD4+)
• Spectral bandwidth (FWHM): ~ 5 cm^-1
• Operating range: 400-2500 nm
• BNF Thickness: 2-4 mm
• Apertures: up to 25×25 mm²
• Angular selectivity: 2-10 mrad
• Incident/Diffracted Angles: 0-45 deg
• Transmittance: up to 95%
• Transmission ripple: <1% at ±0.5 nm from laser line (@633 nm)

Standard Parameters

• Center Wavelength / Transmission: 488nm/75%; 514.5nm/78%;  532nm/80%; 632.8nm/88%;
  785nm/90%; 1064nm/95%
• Available Custom Wavelengths: 405 nm, 442 nm,
  458 nm, 473 nm, 477 nm, 491 nm, 502 nm,
  544 nm, 552 nm, 561 nm, 568 nm, 588 nm,

  Transmission spectrum of OD3@488 nm BragGrate™ Notch Filter with 12×12 mm2 clear aperture.

  
  594 nm, 612 nm, 647 nm, 660 nm, 753 nm,
  840 nm, 905 nm, 976 nm, 980 nm, 1342 nm,
  1352 nm, 1550 nm
• Achievable in any custom wavelengths in the
  range from 405 nm to 2 µm
• Spectral Bandwidth (FWHM): 5-8 cm^-1
• Attenuation: OD3, OD4
• Lateral Dimensions: 11×11 or 12.5×12.5 mm²
• Optional 1-inch round mount
• Thickness: ~2.5 mm

Advantages & Features

• Ultra-narrow rejection bandwidth
  
• Measurements of both Stokes and anti-Stokes modes
  
• No degradation in high power light
• Environmentally stable: high temperature operation,
  no humidity effects
  
• No polarization dependence

Applications

Ultra low-frequency THz Raman spectroscopy

• Raman Imaging
  
• Thomson Scattering