NoiseBlock™ ASE Suppression Filter

Ondax’s NoiseBlock™ ASE (Amplified Spontaneous Emission) Suppression filters suppress the broad spectrum of spontaneous emission that commonly occurs in laser diodes to provide a pure, ASE free, single frequency laser.

Adding a NoiseBlock™ ASE filter to a single frequency wavelength stabilized laser effectively reduces broadband spectral ASE background to more than 70dB below the laser line while transmitting 90% of the single frequency line. The filter’s narrow spectral profile (HWHM <10cm-1) is designed to match the SureBlock™ Ultra Narrow-band Notch Filter, making it ideal for enabling ultra-low frequency (low wavenumber) Raman spectroscopy with high signal-to-noise.

NoiseBlock™ ASE Suppression Filter


  • High transmittance at design wavelength
  • Reduce typical broadband ASE levels to more than 70dB below the laser line
  • Narrow spectral bandwidth
  • Customizable slant angle for angular separation of beams
  • No degradation under high power illumination conditions:
  • Environmentally stable at high temperature and humidity with over 12,000 hours of testing at 150°C
  • Fiber coupled input/output available


  • Removal of broadband ASE, fluorescence, and unwanted laser line emission
  • ASE noise reduction for Raman Spectroscopy
SureBock™ Specifications
Parameter Min Typ Max Unit
Center Wavelength 405 488, 532, 640, 658, 685, 690, 780.25, 785, 808, 830, 976, 1064, 1500 488, 532, 640, 658, 685, 690, 780.25, 785, 808, 830, 976, 1064, 1500 nm
Bandwidth (FWHM)1 0.03 <0.15<10 nmcm-1
Diffraction Efficiency >90 (>70% for 405nm) %
Temperature Dependence 0.01 nm/°C
Total Deflection Angle 8-12 Degrees
Inter-beam Angle γ 2 Degrees
Clear Aperture Diameter 4.5mm in 1/2″ mount. Custom sizes available 25 nm

1Grating bandwidth is a function of wavelength and thickness

Principles of Operation
Principle of Operation

Principles of Operation