| 摘要 |
<p>A quasi-achromatic configuration of two Faraday elements (85, 87) and five birefringent plates (86, 88) which when suitably oriented between two linearly polarizing elements (84, 89) would constitute an optical isolator or circulator. The nominal Faraday rotations of the two elements are 45 DEG and 90 DEG at a center design wavelength about which the devices are to operate. Changes in these rotations due to either wavelength or temperature variations compensate one another because of their coupling by the birefringent plates. In this way a higher degree of isolation is obtained over a wider optical bandwidth than would be possible in a device using a single 45 DEG Faraday element. A group of three plates (86) is used between the two Faraday elements (85, 87) and two more (88) follow them to give the required polarization transformations which must themselves be quasi-achromatic over the desired wavelength range.</p> |
