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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


Combiner figure 1

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.

Combiner figure 2

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)


  • 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,
    Combiner figure 1

    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



Ultra low-frequency THz Raman spectroscopy

  • Raman Imaging
  • Thomson Scattering