In contrast, the simulations indicate a max temperature near 90☌ for a legacy isolator (at 2.3 W). When a Micro Harmonics WR-10 isolator absorbs a 2.3 W signal travelling in the reverse direction, the maximum temperature should not exceed 8☌ above the ambient waveguide block temperature. But we have taken a conservative approach and set the maximum reverse power rating at 2.3 W. Our thermal simulations indicate a maximum reverse power rating of 7 W for our WR-10 isolators. A 7 W RF source gives a max temperature of 50☌. The high thermal conductivity of the diamond disc effectively ties the cone base to the aluminum block temperature. No thermal gradient appears across the diamond disc. The maximum temperature is 24☌ in the left side cone. Our low power Faraday optical isolators use field proven, high efficiency Corning Polarcor polarizers making them ideal for 650, 780, 850 and 980 nm laser diode applications. The resistive layer in the left side cone is treated as a heat source equivalent to the power absorbed from a 1 W RF signal. The graphic to the left shows the result of a thermal simulation of our WR-10 isolator. The thermal conduction path is clearly superior and thus our isolators operate at much lower temperatures. The diamond disc is attached to the metal waveguide block over its periphery and provides an excellent conduit to channel heat away from the resistive layer. This is the optimal location for the diamond disc since it is the region subject to the highest heat levels. The diamond disc is sandwiched between the base of the input cone and the ferrite rod and is in intimate contact over the entire area of the cone base. Diamond is the ultimate thermal conductor approaching 2200 W/m·K, more than five times higher than copper. The diamond disc does not have a hole at the center. But as higher power sources are becoming available there is a renewed interest in the power ratings of these devices.Īt Micro Harmonics we have replaced the input support washer with a uniform high-grade optical CVD diamond disc. Historically this was not an issue as there was very little power available at these frequencies. The resistive layers are thus subject to high heat levels and even damage if too much reverse power is incident on the device. Very little of this heat energy can be channeled away by thermal conduction through the washer-shaped supports, rather it must be dissipated through a radiative process or by means of convection through the surrounding air. The absorbed power is converted to heat energy. Signals entering the output port of the isolator pass through the ferrite rod and are absorbed in the resistive layer bisecting the input side alumina cone. These materials are generally in the class of thermal insulators and thus the cones and ferrite are thermally isolated from the metal block. The support material is typically BOPET, Styrene, a resin or some other material with a low dielectric constant and low loss at mm-wave frequencies. In most commercial Faraday rotation isolators, the ferrite and cones are suspended by a pair of washer-shaped supports as shown in the left-side sketch below. The cones are bisected by a resistive layer along their central axis. The cones are used to couple signals from the waveguides to the ferrite. At the heart of a Faraday rotation isolator are a pair of alumina cones and a ferrite rod. In the isolated direction the beam is split, and then diverged, so it does not focus on the collimator.Diamond Heatsink Technology – Our isolators employ a unique diamond support disc that allows them to handle greater reverse power levels and operate at lower temperatures. In the transmitted direction, the beam is split and then combined and focused into the output collimator. Typically collimators are used on either side of the isolator. The polarization independent isolator is made of three parts, an input birefringent wedge, a Faraday rotator, and an output birefringent wedge.
Hence the angle of polarization will lead to a loss. In optical fiber systems, the polarization direction is typically dispersed in non polarization maintaining systems.
This is because the polarization of the source is typically maintained by the system.
#Faraday isolator free
Polarization dependent isolators are typically used in free space optical systems. The polarization dependent isolator, or Faraday isolator, is made of three parts, an input polarizer, a Faraday rotator, and an output polarizer, called an analyser (polarized at 45°). According to the polarization characteristics, optical isolator can be divided into polarization independent type and polarization dependent type.
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