Abstract: A photon source capable of emitting, for example, a single photon or a single pair of photons on demand. The photon source may include an excitation region where a single instance of a quantum system is excited using excitation energy. A Stimulated Raman Adiabatic Passage (STIRAP) technique can be used for exciting the quantum system to a desired energy level. The photon source may include a photon emission region physically displaced from the excitation region. A transport device can be used for controllably moving an excited quantum system from the excitation region to the photon emission region. The photon emission region may include a resonant cavity tuned to the de-excitation frequency of the quantum system for inducing de-excitation of the quantum system and emission of a photon. The photon emission resonant cavity may be switchably coupled to an output port by a tunable resonant cavity coupling device.

Abstract: A Sagnac interferometer can include a beamsplitter arranged to receive an input beam of light of a design wavelength, to split the input beam of light into first and second beams that counter propagate around an optical path, and to recombine the first and second beams into an output beam of light. The optical path can include at least one diffraction grating that is arranged to satisfy an effective Littrow geometry.

Abstract: A Sagnac interferometer can include a beamsplitter arranged to receive an input beam of light of a design wavelength, to split the input beam of light into first and second beams that counter propagate around an optical path, and to recombine the first and second beams into an output beam of light. The optical path can include at least one diffraction grating that is arranged to satisfy an effective Littrow geometry.

Abstract: A photon source capable of emitting, for example, a single photon or a single pair of photons on demand. The photon source may include an excitation region where a single instance of a quantum system is excited using excitation energy. A Stimulated Raman Adiabatic Passage (STIRAP) technique can be used for exciting the quantum system to a desired energy level. The photon source may include a photon emission region physically displaced from the excitation region. A transport device can be used for controllably moving an excited quantum system from the excitation region to the photon emission region. The photon emission region may include a resonant cavity tuned to the de-excitation frequency of the quantum system for inducing de-excitation of the quantum system and emission of a photon. The photon emission resonant cavity may be switchably coupled to an output port by a tunable resonant cavity coupling device.

Abstract: Systems and methods are disclosed for a modified Sagnac interferometer having a plurality of gratings that can be reflective or transmissive. The gratings allow measurement of wavelength spectra in counter-circulating beams of the interferometer. In one embodiment, diffraction geometries at each pair of neighboring gratings are configured so that diffractive and angular contributions reinforce each other at the second of the pair of gratings. In one embodiment, diffraction geometries at the gratings are configured so that the exiting beams of the interferometer satisfy the crossing condition wherein the exiting beams are on the opposite sides of a reference beam axis for a design wavelength input beam. Also disclosed are techniques for restoring the reinforcement and/or crossing conditions when these conditions are not otherwise met.

Abstract: An apparatus is described that includes an optical storage cavity comprising a planar mirror and a spherically curved mirror that form an optical path therebetween. A pump laser introduces optical pulses into the cavity. A folding mirror is disposed in the optical path between the planar mirror and the spherically curved mirror such that a beam waist is formed between the folding mirror and the second spherically curved mirror. The optical pulses preferably interact with selected particles disposed in the optical path at the waist. The apparatus further comprises a first transducer which adjusts the distance between the spherical mirror and the folding mirror to change a characteristic of the beam waist. A second transducer adjusts the distance between the planar mirror and the spherical mirror to change the optical path length of the cavity. The optical cavity is arranged such that the change in path length due to the second transducer does not significantly affect the characteristic of the beam waist.

Abstract: A Fourier transform spectrometer based on a modified Sagnac interferometer is described. The instrument uses one or more gratings as dispersive elements to greatly improve the spectral resolution, and in-line optics to match the beam size in the interferometer to optimize the efficiency. The resolution can approach about 0.6 GHz at about 632.8 nm (?/??=8.4×105). A CCD or photodiode array is used as the detector and the fast Fourier transform of the fringe pattern is performed by a computer. Some embodiments employ no mechanically moving parts; therefore, they are compact and easy to align. Practical applications include remote sensing, process monitoring, and basic research. The fast response time of the detector also allows real time spectral analysis.

Abstract: A method of generating energetic electromagnetic radiation comprises, during each of a plurality of separated radiation intervals, injecting laser radiation of a given wavelength into an optical cavity that is characterized by a round-trip transit time (RTTT) for radiation of that given wavelength. At least some radiation intervals are defined by one or more optical macropulses, at least one optical macropulse gives rise to an associated circulating optical micropulse that is coherently reinforced by subsequent optical micropulses in the optical macropulse and the electric field amplitude of the circulating optical micropulse at any given position in the cavity reaches a maximum value during the radiation interval.