Pockels Readout Optical Modulator

Principle operating

PROM is a typical optically addressed spatial light modulator (OASLM) with photorefractive Bi12SiO20 (BSO), Bi12GeO20 (BGO) crystals used simultaneously as electro-optic and photoconductive mediums. The basic principle of PROM type modulators is the following. A photosensitive layer detects the writing beam intensity distribution and induces the electron charge distribution inside the crystal. Optical properties of the crystal occur to modify as a function of photo-induced electron charges or photo voltage. The applied electric bias forces to drift the mobile carriers to the crystal / dielectric interface until the electric field in the crystal was cancelled. The photo-induced space charge in BSO, BGO crystals modulates the birefringence through the electro-optic longitudinal Pockels effect. The readout can be realized using a coherent light beam either in transmission or in reflection mode. A new type PROM modulator can be developed, manufactured and supplied for customized applications for selected spectral ranges and incident radiation powers.

Technical characteristics of PROM-020 series

Active areaØ 20 mm
Electro-optic mediumBGO crystal
Thickness of crystal0.2 – 2 mm
Electrodes  S1: Al metal or ITO S2: ITO
Optical internal structureAl (or ITO)/BGO/ITO
PackagePlastic 50X70X30 With connector

The basic advantages of PROM devices on basis of Bi12GeO20 (BGO), Bi12SiO20 (BSO)

  • Opportunity to read efficiently UV, X — ray photons with simple red laser line writing/detection optical system
  • BSO and BGO are simultaneously electro-optic and photoconductive crystals

Applications of PROM modulators

  • Incoherent image enhancement
  • Image or signal correlation
  • Real-time spatial filter generation
  • And two-dimensional logical operations
  • X-ray image detection

PROM-020 modulator in full assembling