There is provided an optical diode comprising a circular polarisation splitter, a first circular polariser and a second circular polariser. The circular polarisation splitter is arranged to receive at least partially unpolarised light and output right-handed circular polarised light along a first optical path and left-handed circular polarised light along a second optical path. The first circular polariser is arranged on the first optical path and transmits right-handed circular polarised light and reflects left-handed circular polarised light. The second circular polariser is arranged on the second optical path and transmits left-handed circular polarised light and reflects right-handed circular polarised light.

The present invention relates to a low-cost LIDAR system. The system may be integrated in a wind turbine for measurement of the approaching wind field. One embodiment relates to a LIDAR system comprising a beam generating section adapted for generating a substantially linearly polarized output beam, and a beam steering section comprising a first optical device for controllably altering the polarization of the output beam, said first optical device in optical connection with a first polarizing beam splitter, said beam steering section adapted for directing the outputbeam interchangeably between a first direction and a second direction.

A translucent sintered body having the following basic composition:
Ca.sub.(1−x)Yb.sub.xF.sub.(2+x), where 0.4≦x≦1.0,
or preferably
Ca.sub.(1−x−y)Yb.sub.xR.sub.yF.sub.(2+x+y), 0.4≦x≦1.0, 0≦y≦0.5 wherein R is at least one element selected from Ce, Pr, Sm, Eu and Y.

The present invention is based on a two-dimensional photonic crystal in which defects are inserted in a controlled manner, has the main function of division of the power of an input signal, excited in one of its six waveguides, among other three waveguides (output ones), while keeping isolation of the input port by means of two other waveguides. The operating principle of the device is based on the alignment of a dipole mode excited in the resonant cavity, in such a way that the nodes of this mode are oriented in the direction of two waveguides, so that these waveguides are not excited. Due to this alignment, each of the three output waveguides receive about one third of the power of input signal. The orientation of dipole mode is controlled by the applied DC magnetic field and the physical and geometrical parameters of the resonator.

An optical device can be used for circularly polarizing light and/or removing reflected light from an optical system (optical isolation). The optical device can have a polarizing-cube including a pair of prisms and a polarizer. Each prism can have two ends linked by an inner face and two outer faces. The prisms can be attached together at the inner face of each with the polarizer sandwiched between the prisms. Fresnel rhomb(s) can be attached to outer face(s) of the prisms.

A time-varying optical metasurface, comprising a plurality of modulated nano-antennas configured to vary dynamically over time. The metasurface may be implemented as part of an optical isolator, wherein the time-varying metasurface provides uni-directional light flow. The metasurface allows the breakage of Lorentz reciprocity in time-reversal. The metasurface may operate in a transmission mode or a reflection mode.

The present invention includes a holding stay made of a heat conductive material that is the same as that of an isolator holder, the holding stay being in contact with a radiation stay made of a member having good thermal conductivity, the radiation stay being in contact with radiation fins extracted from the inside of the isolator holder through an external opening for extraction, columnar welded portions bond the holding stay and the isolator holder through openings for welding, the welded portions apply tensile force toward the isolator holder to the radiation stay via the holding stay, and the radiation stay presses the radiation fins by means of the above-described tensile force to be fixed to the isolator holder.

Photonic rotators integrated on a substrate are disclosed for manipulating light polarization.

Exemplary apparatus and method are provided. In particular, an electromagnetic radiation can be emitted with, e.g. a light source arrangement. For example, the light source arrangement can include a cavity and a filter, and a spectrum of the electromagnetic radiation can be controlled, e.g., with such cavity and filter, to have a mean frequency that changes (i) at an absolute rate that is greater than about 100 terahertz per millisecond, and (ii) over a range that is greater than about 10 terahertz. Additionally or alternatively, the light source arrangement can include a frequency shifting device which can shift the mean frequency of the electromagnetic radiation.

A polarization-independent, optical circulator is formed in silicon photonics. The polarization-independent, optical circulator uses an optical splitter having two couplers and two waveguides joining the two couplers. One of the two waveguides is thinner than the other to create a large effective index difference between TE and TM modes transmitted through the one waveguide. Polarization rotators, including reciprocal and/or non-reciprocal rotators, are further used to create the optical circulator.