113 results about "Electromagnetically induced transparency" patented technology

A magnetometer is provided comprising an atomic vapor in an enclosure, a source of light for preparing the vapor into a state exhibiting electromagnetically induced transparency, a first laser beam passing through the atomic vapor, a phase detector for detecting changes in phase of the first laser beam, and a controller which controls the light source and laser beam and receives the information detected by the phase detector in order to compute from those changes in phase a magnetic field strength in the presence of a selected background magnetic field of at least 0.001 T. Operation in the presence of a background field helps make this magnetometer suitable for diagnostic imaging applications.

The invention discloses a measurement method and measurement device for the intensity of a microwave electric field. The measurement method includes the steps of splitting a probe light generated by a first laser into two beams of identical probe light, one of which enters a rubidium cell and the other of which enters vacuum equipment; coupling light, which is generated by a second laser, entering the rubidium cell, coherently exciting hot atoms in the rubidium cell from a ground state to a rydberg state by the coupling light and the probe light, and realizing electromagnetically induced transparency in an atomic vapor chamber; applying a microwave electric field generated by a microwave source onto the hot atoms, and coupling another adjacent rydberg state onto a three-level EIT system to form a four-level system; and respectively probing the two ways of transmission light emitted from the rubidium cell and the vacuum equipment, determining the time difference of the two ways of transmission light by analyzing a dispersion relation between the two ways of transmission light, and thus obtaining the intensity of the microwave electric field.

We introduce a new all-optical mechanism that can compress the bandwidth of light pulses to absolute zero, and bring them to a complete stop. The mechanism can be realized in a system consisting of a waveguide side-coupled to tunable resonators, which generates a photonic band structure that represents a classical analogue of the Electromagnetically Induced Transparency. The same system can also achieve a time-reversal operation. We demonstrate the operation of such a system by finite-difference time-domain simulations of an implementation in photonic crystals.

The invention provides an angle measuring device and an angle measuring method of a double-frequency laser interferometer based on a slow-light material, which relates to an angle measuring device and an angle measuring method of the double-frequency laser interferometer. The angle measuring device provided by the invention aims at solving the problem of low angle measuring sensitivity of the angle measuring device of the existing double-frequency laser interferometer. Double-frequency laser is divided into polarized light with frequency at v1 and polarized light with frequency at v2 through a polarization spectroscope in a polarization direction. The polarized light with the frequency at v1 enters a pyramid prism 1 to be reflected to the polarization spectroscope through the pyramid prism 1; the polarized light with the frequency at v2 is reflected to the slow-light material sequentially through a common corner reflector, the slow-light material and a pyramid prism 2 and then is reflected to the polarization spectroscope sequentially through the slow-light material and the common corner reflector to converge with polarized light reflected through the pyramid prism 1 at the position of the polarization spectroscope so as to form beat frequency; and converged light enters an optical detection face of a photoelectric detector after being subjected to transmission of a polarization reducing device. The angle measuring device and the angle measuring method provided by the invention are applicable to the electromagnetic induction transparency technology and the spectral hole burning technology.

A magnetometer is provided comprising an atomic vapor in an enclosure, a source of light for preparing the vapor into a state exhibiting electromagnetically induced transparency, a first laser beam passing through the atomic vapor, a phase detector for detecting changes in phase of the first laser beam, and a controller which controls the light source and laser beam and receives the information detected by the phase detector in order to compute from those changes in phase a magnetic field strength in the presence of a selected background magnetic field of at least 0.001 T. Operation in the presence of a background field helps make this magnetometer suitable for diagnostic imaging applications.

A variable semiconductor all-optical buffer and method of fabrication is provided where buffering is achieved by slowing down the optical signal using a control light source to vary the dispersion characteristic of the medium based on electromagnetically induced transparency (EIT). Photonic bandgap engineering in conjunction with strained quantum wells (QWs) and quantum dots (QDs) achieves room temperature operation of EIT. Photonic crystals are used to sharpen the spectral linewidths in a quantum well structure due to its density of states and in a quantum-dot structure caused by the inhomogeneity of the dot size, typically observed in state-of-the-art QD materials. The configuration facilitates monolithic integration of an optical buffer with an amplifier and control laser to provide advantages over other material systems as candidates for optical buffers.

The invention provides a method and device for improving the microwave electric field intensity measurement signal-to-noise ratio through Zeeman frequency modulation. The method comprises the following steps: the frequency of coupling light is locked on the resonance transition of the intermediate state and the Rydberg state 1; the microwave frequency is locked on the resonance transition of the Rydberg state 1 and the Rydberg state 2, the frequency of the detection light is scanned near the resonance transition frequency of the ground state and the intermediate state, and the spectrum of thedetection light after penetrating through an atom pool is measured so as to obtain the spectrum of the AT split signal of the Rydberg electromagnetic induction transparency EIT; the position of the atomic energy level of the sample is modulated by using an alternating-current magnetic field, and frequency modulation is performed on the spectrum; and the spectrum of the AT split signal of the Rydberg electromagnetic induction transparent EIT is demodulated to obtain a dispersive frequency discrimination signal of the EIT-AT split spectrum. According to the method and device, the atomic energy level is modulated through the alternating magnetic field, frequency modulation is equivalent to spectrum frequency modulation, the problem of residual amplitude does not exist naturally, and meanwhilean experiment system is simpler and more convenient.

A system, method, and apparatus for delayed optical router based on slow light and nondegenerate four-wave mixing processes are presented, in which three laser pulses interact with a three-level nonlinear optical medium composing two closely spaced ground states and an excited state. The delayed optical routing mechanism is based on a slow light phenomenon, in which a group velocity of an incoming input signal pulse is slowed down due to quantum coherence induced refractive index change. The two-photon coherence induced on the ground states via electromagnetically induced transparency is optically recovered via nondegenerate four-wave mixing processes. The nondegenerate four-wave mixing generation is enhanced owing to absorption cancellation. In this case, the individual pulse switching / routing time is limited by the coherence decay time that is much faster than population decay time, where the population decay-time is a limiting factor of conventional switching devices. In the present invention of the delayed optical router the overall switching / routing time, however, is controlled to be delayed by using the slow light. Even though the overall switching / routing time can be delayed, the switching bandwidth of the present invention is not degraded at all because the input and output signal's group velocity across the delayed optical router is still same. Therefore, the present invention of the delayed optical router gives an advantage of wide-bandwidth optical data traffic control using a narrow-bandwidth processing unit such as an electronic device. Another advantage is signal amplifications owing to the dark-resonance enhanced nondegenerate four-wave mixing processes.

The invention provides an atomic oscillator which improves S / N by improving energy level of light absorbed by a photodetector. The atomic oscillator (50) mainly includes a cell (2) containing a mixture gas of alkali metal atoms and isotopes of the alkali metal atoms, a light source (LD) (1) that has coherency and irradiates the gas with lights including a first resonant light pair having two different frequency components for one center frequency and a second resonant light pair having two different frequency components for one center frequency, a photo detector (PD) (3) that generates a detection signal corresponding to intensity of light passing through the gas, and a frequency control part (12) that controls, based on the detection signal, frequencies of the first resonant light pair to cause an electromagnetically induced transparency phenomenon to occur in the alkali metal atom and controls frequencies of the second resonant light pair to cause the electromagnetically induced transparency phenomenon to occur in the isotope of the alkali metal atom.

An atomic oscillator using an electromagnetically induced transparency phenomenon caused by irradiation of a resonant light pair to an alkali metal atom, includes: a light source that generates a first light having a center frequency f1 and a plurality of frequency components different from each other in frequency by Δf, and a second light having a center frequency f2 and a plurality of frequency components different from each other in frequency by Δf; a light detection unit that detects intensities of lights including the first light and the second light passing through the alkali metal atom; and a control unit that controls, based on a detection result of the light detection unit, to cause a frequency difference between a specified frequency component of the first light and a specified frequency component of the second light to be equal to a frequency corresponding to an energy difference between two ground levels of the alkali metal atom, wherein a frequency difference between the center frequency f1 of the first light and the center frequency f2 of the second light is different from the frequency corresponding to the energy difference between the two ground levels of the alkali metal atom.

A quantum interference device causing electromagnetically induced transparency in an alkali metal atom includes: a light source generating first and second resonant lights with frequency differences Δω; a magnetic field generator applying a magnetic field to the atom; a light detector detecting intensities of the first and second resonant lights passing through the atom; and a controller causing a frequency difference between specified first and second resonant lights to equal a frequency difference corresponding to an energy difference between two ground levels of the atom based on the detected light. The controller causes the frequency Δω or magnetic field intensity to satisfy 2×δ×n=Δω or Δω×n=2×δ. The frequency δ corresponds to an energy difference between two Zeeman split levels differentiated by one magnetic quantum number and generated in the two ground levels of the atom by energy splitting.

A system, method, and apparatus for delayed optical router based on slow light and nondegenerate four-wave mixing processes are presented, in which three laser pulses interact with a three-level nonlinear optical medium composing two closely spaced ground states and an excited state. The delayed optical routing mechanism is based on a slow light phenomenon, in which a group velocity of an incoming input signal pulse is slowed down due to quantum coherence induced refractive index change. The two-photon coherence induced on the ground states via electromagnetically induced transparency is optically recovered via nondegenerate four-wave mixing processes. The nondegenerate four-wave mixing generation is enhanced owing to absorption cancellation. In this case, the individual pulse switching / routing time is limited by the coherence decay time that is much faster than population decay time, where the population decay-time is a limiting factor of conventional switching devices. In the present invention of the delayed optical router the overall switching / routing time, however, is controlled to be delayed by using the slow light. Even though the overall switching / routing time can be delayed, the switching bandwidth of the present invention is not degraded at all because the input and output signal's group velocity across the delayed optical router is still same. Therefore, the present invention of the delayed optical router gives an advantage of wide-bandwidth optical data traffic control using a narrow-bandwidth processing unit such as an electronic device. Another advantage is signal amplifications owing to the dark-resonance enhanced nondegenerate four-wave mixing processes.

The invention discloses a multi-band electromagnetic induction transparent structure based on a terahertz metamaterial. The structure comprises a first dielectric substrate, a second dielectric substrate, a first metal strip, a second metal strip, a first metal symmetrical split-ring resonator and a second metal symmetrical split-ring resonator, wherein the second dielectric substrate is located below the first dielectric substrate, the first metal symmetrical split-ring resonator is located between the first metal strip and the second metal strip, and the second metal symmetrical split-ring resonator is located on the side, which is away from the first metal symmetrical split-ring resonator, of the second metal strip. Under the condition of incident electromagnetic field excitation, the metal strips and electromagnetic waves are in strong coupling to serve as bright-mode resonance; the metal symmetric split-ring resonators and electromagnetic waves are in weak coupling to serve as dark-mode resonance. Based on the coupling of the multi-band electromagnetic induction transparent structure based on the terahertz metamaterial and the incident electromagnetic field, a multi-band electromagnetic induction transparent phenomenon can be realized by a bright and dark mode near-field coupling principle.