In Faraday Effect, the phase modulation of two mutually perpendicular components of linearly polarized light results into polarization modulation, which is then transformed into Amplitude Modulation by analyzer. The magneto-optic modulators are based on the rotation of optical polarization as light propagates along the magnetic field in a material, by the Faraday effect. Like intensity modulation, polarization modulation does not require sophisticated stabilized laser. Since, the optical sensitivity of a polarization modulated light is about twice as high as intensity modulated signal, it provides better receiver Signal to noise ratio (SNR).
Our modulator is made of MR3-2 Faraday material placed inside a solenoid coil with modulating electric current. Water cooling system is used for longer operation, for which water inlet and outlet connectors are provided on top of the device.
Since glass material in high power laser system is damaged as a consequence of self focusing, low non-linear refractive index as well as high Verdet constant are important factors for Magnetic Optical Glass. The MR3-2 glass is made by considering all these factors and is stable, sensitive and inherently immune to interference.
HO-FM20C Faraday Modulator
The optical Specifications :
Faraday Rotator Glass : MR3-2 glass
Verdet constant : -0.329 min / Oe*cm at 632.8nm and -0.108 min / Oe*cm at 1064nm
Absorption coefficient : < 0.002 per cm at 1064nm
Transmission : ≥ 86% without AR coating
Bulk laser damage threshold for material : > 25 (Joules/cm²) at 1064nm, 10ns pulses
For stress birefringence, extinction ratio to perpendicular polarization > 40 dB
Water Cooler for Faraday Modulator
Wavelength Range (nm)
380 - 1100nm
200 - 5000Hz
Resolution : +/- 1Hz
Polarimetry & Other Optical Rotation Measurements
Magneto-Optic Kerr Effect
Faraday Modulation Spectroscopy (FAMOS)
The Faraday modulator used for the polarimeter have important function other than providing an easy way of optimizing the signal to noise ratio; it allows the real and imaginary parts of the refractive indices to be separated. This stems from the fact that in the modulator there is very little absorption i.e. the effect is only to modulate the angle of rotation of the linearly polarized laser beam with negligible modulation of the phase or ellipticity of the light.
Faraday Isolator (Optical Isolator)
Faraday isolators are optical components which allow light to travel in only one direction. Their mode of operation is based on the non-linear Faraday effect (magneto rotation). In principle, the function of an optical isolator is analogue to that of an electrical diode. Faraday isolators are composed of three elements: entrance polarizer, Faraday rotator and exit Polarizer.
They are used to protect a laser source from destabilizing feedback or actual damage from back-reflected light. The 5mm aperture Faraday isolators are cylindrically-shaped magneto-optic devices. Strong Neodymium Iron Boron permanent magnets are used to generate high axially-oriented fields within the magnet housing.
In operation, the magnet housing is sandwiched between input and output polarizers that have their transmission axis oriented 90 degrees relative to each other. In the reverse direction the backward traveling beam has a polarization orthogonal to the input polarizer and is therefore crossed with it, resulting in a rejected beam exiting the input polarizer.
We also provide custom designed isolators, based on your requirements. Please feel free to contact us.
Min / Typical
|Polarizer Type||Rotating Medium||Power Handling|
|HO-FI410||410 nm||5 mm||80 / 82 %||30 dB||Calcite||MR3-2
( Joules/cm² )
at 1064 nm
10 ns pulses
|HO-FI532||532 nm||85 / 89 %||36 / 40 dB|
|HO-FI632||632.8 nm||85 / 89 %||36 / 38 dB|
|HO-FI650||650 nm||85 / 89 %||36 / 38 dB|
|HO-FI785||785 nm||85 / 89 %||36 / 38 dB|