The present invention discloses an encoding apparatus, including: a polarization splitter-rotator PSR, a polarization rotation structure, and a modulator, where the PSR is configured to receive an input signal light, split the input signal light into two parts whose polarization modes are the same, and send the two parts to the polarization rotation structure and the modulator respectively; the polarization rotation structure has functions of rotating, by 180 degrees, a polarization direction of an optical signal entering the polarization rotation structure from one end, and keeping a polarization direction of an optical signal entering the polarization rotation structure from the other end unchanged; the modulator is configured to modulate a light input to the modulator; and the PSR is further configured to receive signal lights sent by the polarization rotation structure and the modulator, combine the two signal lights to send the output signal light.

An optical isolator device with minimized polarization mode dispersion includes a first polarization splitter/combiner, a non-reciprocal polarization rotator and a second polarization splitter/combiner. Only forward propagation of light is allowed to propagate in the device, with backward optical signal blocked due to non-reciprocal polarization rotation. The optical paths of o-ray and e-ray are arranged to achieve equal optical path lengths, which makes polarization mode dispersion minimal to nonexistent. When symmetrically configured, both polarization mode dispersion (PMD) and polarization dependent loss (PDL) become zero in principle.

A small integrated free space circulator, comprising a first polarizing beam splitter (1), a half-wave plate (2), a Faraday rotating plate (3), a beam splitter (4), a quarter-wave plate (5), and a pair of reflective plates (6, 7), wherein the first polarizing beam splitter (1), the half-wave plate (2), the Faraday rotating plate (3), and the beam splitter (4) are sequentially arranged, the quarter-wave plate (5) and the reflective plate (6) are sequentially attached to a side surface of the first polarizing beam splitter (1) adjacent to the half-wave plate (2), and the reflective plate (7) is arranged on a side surface of the beam splitter (4, 8) adjacent to or opposite to the Faraday rotating plate (3); when the reflective plate (7) is arranged on the side surface of the beam splitter (8) opposite to the Faraday rotating plate (3), the reflective plate (7) partially covers the side surface of the beam splitter (8) opposite to the Faraday rotating plate (3). By means of an organic combination of optical elements such as the polarizing beam splitters (1, 4), the wave plates (2, 5), the Faraday rotating plate (3), the reflectors (6, 7), and the birefringent crystal (8), the device has advantages such as small volume, high integration, easy production, and low cost, and has a good market prospect.

An optical device includes an optical amplifier that optically amplifies incident light, a first isolator that is arranged on an input stage of the optical amplifier and inputs the incident light to the optical amplifier, and a second isolator that is arranged on an output stage of the optical amplifier and receives input of incident light that has been optically amplified by the optical amplifier. The first isolator inputs, to the optical amplifier, first linearly-polarized incident light that is converted from randomly-polarized incident light and that has been transmitted. The second isolator, when reflected light of the first linearly-polarized incident light that has been optically amplified by the optical amplifier is input from a reverse direction, converts reflected light of the first linearly-polarized incident light to reflected light of second linearly-polarized light that is orthogonal to the reflected light of the first linearly-polarized incident light.

Embodiments of synthetic garnet materials having advantageous properties, especially for below resonance frequency applications, are disclosed herein. In particular, embodiments of the synthetic garnet materials can have high Curie temperatures and dielectric constants while maintaining low magnetization. These materials can be incorporated into isolators and circulators, such as for use in telecommunication base stations.

The present application relates to an optical isolation device. The present application provides an optical isolation device having a high transmittance in a forward direction and an excellent isolation ratio. Such an optical isolation device can be applied to various applications such as the field of optical communication or laser optics, the field of security or privacy protection, brightness enhancement of displays, or a use for hiding and covering.

An optical isolator for generally collimated laser radiation includes a single polarizing element, at least one Faraday optical element, at least one reciprocal polarization altering optical element disposed at the single polarizing element, at least one reflective optical element for reflecting radiation to provide an even number of passes through the at least one Faraday optical element, and a magnetic structure. The magnetic structure is capable of generating a magnetic field within the at least one Faraday optical element that is generally aligned with the even number of passes along a beam propagation axis. The optical isolator is configured to receive generally collimated laser radiation, which passes through the single polarizing element and the at least one reciprocal polarization altering optical element and which makes at least two passes through the at least one Faraday optical element, whereby generally collimated laser radiation is output from the optical isolator.

Disclosed are integrated photonics systems including integrated polarizing devices for implementing on-chip optical isolators and circulators. Implemented around a Faraday rotator isolator arrangement, integrated photonic components are arranged in a device to polarize and rotate the polarization of optical signals traversing forwards and backwards through the device to effect optical isolators and circulators.

A magnetic field sensor comprises a magnetically responsive light propagating component configured to cause a polarization of light propagating inside the component to be rotated in response to an applied magnetic field, wherein the magnetically responsive light propagating component is formed of a bulk material doped with a dopant, the dopant including at least gadolinium, the dopant concentration being at a sufficiently low concentration such that the dopant is uniformly dispersed in the bulk material to provide a high Verdet constant. The magnetic field sensor also comprises a detector, and a polarization-maintaining light input device to couple the light into the magnetically responsive light propagating component. The detector is configured to measure a property of light output from the magnetically responsive light propagating component to determine a change in polarization of the light, the change caused by the presence of a magnetic field.

Embodiments of synthetic garnet materials having advantageous properties, especially for below resonance frequency applications, are disclosed herein. In particular, embodiments of the synthetic garnet materials can have high Curie temperatures and dielectric constants while maintaining low magnetization. These materials can be incorporated into isolators and circulators, such as for use in telecommunication base stations.