Optical isolators for high-power 1.06-micron glass laser systems

Magnetoactive media for cryogenic Faraday isolators

“…Bearing in mind that the angle of rotation of the radiation polarization plane in MOE φ is defined by the formula (FR) [8]…”

“…The radiation was transmitted through vacuum window (3) to the CFI, which is the MOE (5) in magnetic system (4) placed in optical cryostat (2) [6]. Further, the major portion of the radiation was passed to absorber (8), and part of the radiation with power of ∼10 3 times attenuated by a couple of quartz wedges (6) was passed to Glan prism (7) fastened to the optical table with a limb and recorded by CCD camera (9). The angle of rotation of the radiation polarization plane, φ, was equal to the angle of turn of Glan prism at which minimum radiation intensity was registered.…”

“…The Verdet constant of paramagnetic materials increases on cooling [6][7][8]. Besides, other thermo-optical characteristics of the medium also improve with decreasing temperature.…”

High-power lasers

“…The system is interspersed with Faraday isolators (Leppelmeier andSimmons 1973, Padula andYoung 1967) which use high Verdet constant glass (e.g. Hoya FR5, V=0*0826 min Oe-1 cm-1, see Hoya Glass Works Ltd (1976)) to give 45" rotation with N 1.5 cm glass thickness in pulsed magnetic fields of 22 T. These isolators have N 300 : 1 suppression of feedback and prevent self-oscillation of any part of the chain or damage when a substantial fraction of the laser power is recollimated and reflected back into the laser when the beam is focused onto a target.…”

Characterization of the terbium-doped calcium fluoride single crystal

“…The Verdet constant of paramagnetic materials is increasing with the cooling [8][9][10][11]. Furthermore, other thermooptical characteristics are improving with the temperature decreasing.…”