113 results about "Electromagnetically induced transparency" patented technology

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.

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.

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.