88 results about "Orbital angular momentum of light" patented technology

The present invention describes a system and method of OAM diverse signal processing using classical beams for applications in which OAM signal character is controlled such as optical tagging and applications in which OAM signal character is not controlled such as clutter mitigation and interference cancellation for target detection, identification etc. This is accomplished by transmitting a source beam having a prescribed state with one or more non-zero OAM components, reflecting the beam off a ‘tagged’ or ‘untagged’ target and receiving the return beam in the direct return path to measure the one or more OAM components to identify the target. OAM processing provides additional degrees of processing freedom to greatly enhance the processing capabilities to detect and identify both ‘tagged’ and ‘untagged’ targets.

A phase plate including a plurality of surfaces arranged around a symmetry axis to reflect an incident electromagnetic field having a null orbital angular momentum, thereby generating a reflected electromagnetic field having an orbital angular momentum. The surfaces are arranged such that, with respect to a cylindrical reference system in which the azimuthal coordinate is measured in a plane perpendicular to the symmetry axis, the respective heights define a non-monotonic azimuthal profile, so that the reflected electromagnetic field forms an optical vortex whose topological charge is not associated one-to-one to the orbital angular momentum.

The invention relates to a free space laser communication system based on the orbital angular momentum of light beams, which belongs to the technical field of optical applications. The free space laser communication system consists of an optical fiber closely arranged laser, four convex lenses, two polarizers, a space optical modulator, a pinhole diaphragm, a beam expansion system, a composite binary amplitude grating and a CCD detector. The free space laser communication system takes the optical fiber closely arranged laser with gate control as a light source, designs a phase diffraction grating loaded onto the space optical modulator according to the distribution of the light beams emergent from the optical fiber closely arranged laser, and leads all the light beams to respectively havedifferent diffraction orders and be positioned on a central shaft of the system, thereby constructing a central diffraction light beam carrying gate information of the optical fiber closely arranged laser. When the system works, the gate control is carried out on the optical fiber closely arranged laser according to data to be transmitted for realizing the modulation loading of the data to be transmitted; and the light beams carrying data information utilize the composite binary amplitude grating to detect the orbital angular momentum state of the light beams at the receiving end of the system after transmitting for a certain distance in free space, thereby completing the demodulation of the data transmitted by the communication system.

The invention provides a circularly polarized OAM (orbital angular momentum) reflect array antenna. The circularly polarized OAM reflect array antenna is used for improving interference rejection of the antenna and comprises a feed source antenna unit and a reflector, wherein the feed source antenna unit adopts a circularly polarized antenna, the radiation direction of the feed source antenna unitfaces one side, where a radiation patch is printed, of each dielectric material on the reflector, and the feed source antenna is fixed relative to the reflector; the reflector comprises N*N radiationunits which are arranged equidistantly and periodically, N is larger than or equal to 2, each radiation unit comprises a dielectric material plate, the radiation patch printed on one side surface ofthe dielectric material plate and a metal floor arranged on the other side surface, the phase of each radiation unit is determined according to a phase compensation formula of the circularly polarizedOAM reflect array antenna, and compensation of each phase is realized by a rotating unit; each radiation patch comprises two concentric ring patches, a pair of rectangular gaps are formed in an axispassing through the circle center of each ring patch, and an antenna phase shift curve is controlled by adjusting radius of each outer ring patch.

The invention discloses a generation system and a generation method for a spinning-orbital angular momentum hybrid entangled state. The system consists of a single photon source, a spinning-orbital angular momentum conversion unit, a spinning-orbital angular momentum hybrid entangled state separation unit and a feedback compensation unit, wherein the spinning-orbital angular momentum hybrid entangled state separation unit obtains spinning-orbital angular momentum hybrid entangled state photons through a polarization beam splitter, a polarization controller and a Q-plate phase plate; the separation unit realizes separation of horizontal polarization single photons from the spinning-orbital angular momentum hybrid entangled state photons through two beam splitters, two full reflectors and two dove prisms; the feedback compensation unit feeds back and transmits non-converted horizontal polarization light to the spinning-orbital angular momentum conversion unit for further conversion. The generation system disclosed by the invention realizes high-efficiency conversion of a high-purity spinning-orbital angular momentum hybrid entangled state, so that the system cost and the communication error rate are reduced, and the security of the system is enhanced.

The invention discloses a novel composite grating and a method and device using the grating to detect orbital angular momentum state of multiplexing vortex light beams. When the vortex light beams are irradiated to the composite grating, the orbital angular momentum state of the vortex light beams can be obtained by observation of the position where gauss beams occur in a far-field diffraction pattern. The measuring range of the orbital angular momentum state of the composite grating is -24 to +24, and the range can satisfy detection of multiplexing vortex light beams under most circumstances. Using the composite grating can rapidly detect all orbital angular momentum components of the multiplexing vortex light beams, and when different multiplexing vortex light beams are incident, a light path does not need to be readjusted, so the operation is extremely simple and convenient. The novel composite grating and the method and device using the grating to detect the orbital angular momentum state of the multiplexing vortex light beams are of great significance to research of future photo-communication, optical tweezers technology, quantum communication and the like.

The invention relates to methods, devices, systems and uses of such systems for the generation and detection of electromagnetic fields carrying orbital angular momentum. An electromagnetic wave placed in a resonator having a closed-loop waveguide supporting a guided wave propagating at resonance with angular order, p, and with an angular grating patterned in the closed-loop waveguide, the angular grating having a integer number, q, of grating elements. The angular grating selectively couples the guided wave mode to a free space radiation mode having an OAM quantity, l, and out-of-plane wave vector component, krad,z, and wherein significant coupling to the grating occurs only when the following wave matching condition is satisfied: l=p−mq where: m is the diffraction order of the angular grating, m=1, 2, 3, . . . ,.

The invention belongs to the field of radar detection and Doppler detection of moving targets and particularly relates to a method of detecting a compound motion target based on orbital angular momentum. The method comprises the steps: designing a radar emission signal, and establishing an emission signal model; setting target motion parameters, acquiring a target echo equation by deduction, and analyzing with the target echo equation to obtain internal relations of Doppler frequency offset to target translational velocity and rotational angular velocity; providing a detection and separation method of translational Doppler frequency offset and rotational Doppler frequency offset; finally, implementing detection of the compound motion target based on the detection results of Doppler frequency offset. orbital angular momentum information carried by vortex electromagnetic wave can be utilized herein to provide effective detection and separation for translational Doppler and rotational Doppler, so that the detection of the compound motion target is implemented; references are provided for the development of radar detection techniques and target recognition techniques based on orbital angular momentum.

A method and system for optical angular momentum (OAM) spectroscopy includes generating a beam of light having a single OAM mode. A first spectrum of the beam of light is detected and the beam of light is passed through a gas to attenuate the beam of light in accordance with a presence and concentration of a respective gas. A second spectrum the beam of light is coherently detected and a difference between the first and second spectrum for the beam of light is analyzed to determine the presence and concentration of the respective gas.

According to a modulation method for improving the satellite communication spectrum efficiency, a communication system with one transmitting antenna and a plurality of receiving antennas is used, thetransmitting end is provided with a traveling wave annular resonant cavity antenna, and the antennas generate OAM waves of different modes; a part of the to-be-sent information is mapped into an orbital angular momentum signal mode, namely an OAM wave of a certain mode, the other part of the to-be-sent information is modulated into a traditional digital modulation symbol through a P-point constellation diagram, an orbital angular momentum signal in a specific mode is used for transmitting the digital modulation symbol at each transmission time, and the modulation process or method comprises the three processes of orbital angular momentum mode modulation mapping, the orbital angular momentum mode detection and the digital modulation and demodulation. According to the present invention, thenew dimension of the orbital angular momentum is added in satellite communication transmission, the frequency spectrum efficiency is improved, and due to the orthogonality between the orbital angularmomentum signals of different modes, the influence of inter-channel interference is avoided, and the safety of information transmission can be enhanced.

The invention discloses an optical orbital angular momentum signal demodulation device and method. The optical orbital angular momentum signal demodulation device comprises a modulation module, a beam splitter, a slit, a first photoelectric converter, a reflector, a second photoelectric converter and a demodulation module which are sequentially arranged along an optical path transmission direction; the modulation module generates N orbital angular momentum modulated beams in a vortex state; the orbital angular momentum modulated beams are divided into a first beam and a second beam by the beam splitter; after being filtered by the slit, the first beam is converted into a first electric signal by the first photoelectric converter; after being reflected by the reflector, the second beam is converted into a second electric signal by the second photoelectric converter; the demodulation module obtains an energy ratio of the first beam and the second beam according to the first electric signal and the second electric signal, and demodulates out a corresponding orbital angular momentum signal; by using the energy ratio of the light passing through the slit and the light which does not pass through the slit, the orbital angular momentum signal can be directly demodulated; and the optical orbital angular momentum signal demodulation device and method have the advantages of simplicity and high efficiency.

The invention discloses a detection device and method for the orbital angular momentum value. The detection device comprises a half wave plate, a spatial light modulator, a focusing lens and a CCD camera which are sequentially arranged along the light beam propagation route. The spatial light modulator and the CCD camera are both connected with a computer. According to the detection method, the orbital angular momentum value of an incidence spiral light beam is obtained by observing the position of a Gaussian hot spot in a far-field diffraction pattern and judging the diffraction level where the Gaussian light beam is located. The detection device has the advantages of being simple in structure and capable of conveniently conducting detection.

The invention discloses a method for generating a non-diffracting Airy beam carrying orbital angular momentum. The method includes the steps of: 1) emitting a Gaussian beam from a laser and collimating and expanding the Gaussian beam; 2) projecting the collimated and expanded Gaussian beam onto a spectroscope to be split; 3) loading a helical cubic phase diagram carrying an orbital angular momentum factor on a spatial light modulator; 4) injecting the split beam into the spatial light modulator with the helical cubic phase diagram to be subjected to phase modulation; 5) performing Fourier transform on the phase-modulated beam through a Fourier lens to obtain a non-diffracting Airy beam carrying the orbital angular momentum. The invention also relates to a device for generating a non-diffracting Airy beam carrying orbital angular momentum.

A laser device is provided for generating a helical-shaped optical wave and includes: (i) a gain region located between one first end defined by a first mirror and a second end defined by an exit region, (ii) a second mirror arranged so as to form with the first mirror an optical cavity including the gain region and a gap between the exit region and the second mirror, (iii) apparatus for pumping the gain region so as to generate the optical wave, wherein the laser device further includes at least one apparatus for shaping the light intensity and/or phase profiles of the optical wave and arranged for selecting at least one rotary-symmetrical transverse mode of the optical wave, the rotary-symmetrical transverse mode being chosen between those with a radial index equal to zero and with an azimuthal index being an integer with a module higher or equal to 1.

The invention belongs to the technical field of communication, and particularly relates to a honeycomb meta-material surface capable of generating orbital angular momentum waves. The honeycomb meta-material surface is formed by arranging six kinds of meta-material elements. Each kind of elements is arranged and distributed in six regions in the plane. Each region has 120 meta-material elements. All the regions have the same diamond shape. The centers of the meta-material elements in the six regions are arranged in the same way, and form a hexagonal shape. Each meta-material element is composedof four dielectric substrates, four metal patches and a metal slit layer which are stacked alternately, wherein the four dielectric substrates are stacked from top to bottom, the four metal patches are regular hexagons of the same size and are distributed on the upper and lower surfaces and in the inter-layers of the dielectric substrates, and each metal patch is aligned with the center of the slit. The meta-material surface of the invention can convert plane waves entering in any polarization mode into orbital angular momentum waves, and orbital angular momentum wave of different modes can be formed by changing the arrangement mode of the meta-material elements. The honeycomb meta-material surface has the advantages of flexible design, simple structure, low cost, and the like.

The invention provides a light beam orbital angular momentum generating device which is used for generating corresponding angular momentum to at least one light beam. The light beam orbital angular momentum generating device comprises a first lens, a second lens, silicon-based liquid crystal, a third lens and a fourth lens. A telescope system combined by the first lens and the second lens amplifies at least one light beam. The silicon-based liquid crystal is divided into multiple partitions, and the number of the partitions correspond to that of the light beams. The silicon-based liquid crystal allows the amplified light beams to generate orbital angular momentum corresponding to partition number. A telescope system combined by the third lens and the fourth lens sends out the light beams generating orbital angular momentum. The light beam orbital angular momentum generating device has the advantages that the silicon-based liquid crystal is divided into multiple partitions, the light beams respectively enter the partitions, the number of the partitions equals to that of the light beams, the phase of each partition is the spiral phase different in level, multiple light beams and multi-level spiral phases can be generated, and number of the silicon-based liquid crystal can be reduced effectively.

The invention discloses a three-dimensional synthetic aperture radar imaging method based on electromagnetic vortex waves. The method mainly solves the problem that according to existing two-dimensional imaging methods, only relative stillness of an object and a radar is taken into consideration. The method comprises the steps that 1, the electromagnetic vortex waves with different orbital angularmomentum are emitted; 2, range compression and range migration correction are conducted on received echo signals; 3, deramping operation is conducted in the heading direction to obtain a focus imagein the heading direction; 4, the scene center is regarded as reference, and Doppler cell migration correction is conducted on the focused image in the heading direction; 5, Fourier transformation is conducted in an orbital angular momentum field to obtain a three-dimensional image, and then according to angle transformation relations, a final three-dimensional synthetic aperture radar image is obtained. According to the method, by means of the orbital angular momentum carried by the electromagnetic vortex waves in combination with relative motions of the object and the radar, three-dimensionalsynthetic aperture radar imaging is achieved.

The invention discloses a phase plate capable of producing light orbital angular momentum superposition. The phase plate capable of producing light orbital angular momentum superposition comprises a core phase modulating structure (1) and encapsulating materials (2); the thickness l of the core phase modulating structure changes along with the azimuth angle phi and meets A, wherein l0 is the thickness of a base, ls is phase step thickness, and alpha is a variable angle; the core phase modulating structure can modulate the phase of a light field; the encapsulating materials are mounted outsidethe core phase modulating structure for protecting the core phase modulating structure. When the phase plate capable of producing light orbital angular momentum superposition is in work, laser carrying single orbital angular momentum is perpendicularly incident into the phase plate and then passes through the core phase modulating structure, and accordingly the phase of the laser is modulated andthe laser is converted into light carrying superposed orbital angular momentums.