An optical apparatus includes a diffractive optical element (DOE), having at least one optical surface, a side surface, which is not parallel to the at least one optical surface of the DOE, and a grating, which is formed on the at least one optical surface so as to receive and diffract first radiation from a primary radiation source that is incident on the grating. The apparatus further includes at least one secondary radiation source, which is configured to direct second radiation to impinge on the side surface, causing at least part of the second radiation to propagate within the DOE while diffracting internally from the grating and to exit through the side surface. The apparatus also includes at least one radiation detector, which is positioned so as to receive and sense an intensity of the second radiation that has exited through the side surface.

A method for obtaining transient Bragg gratings in optical waveguides and several different applications of the transient Bragg gratings obtained using this method are presented. The basic mechanisms for obtaining the transient gratings in the waveguides are refractive index change due to Kerr nonlinearity, free carrier generation, and gratings formed by linear or non-linear absorption of thermal energy. The exemplary applications include an ultra-fast fiber laser source at any central wavelength, a fast spectral switch/modulator, transient pulse stretchers based on transient chirped gratings, Q-switching based on transient gratings, and time reversal of ultra-short pulses and low power sub-nanosecond pulse generations.

A method for obtaining transient Bragg gratings in optical waveguides and several different applications of the transient Bragg gratings obtained using this method are presented. The basic mechanisms for obtaining the transient gratings in the waveguides are refractive index change due to Kerr nonlinearity, free carrier generation, and gratings formed by linear or non-linear absorption of thermal energy. The exemplary applications include an ultra-fast fiber laser source at any central wavelength, a fast spectral switch/modulator, transient pulse stretchers based on transient chirped gratings, Q-switching based on transient gratings, and time reversal of ultra-short pulses and low power sub-nanosecond pulse generations.

A guided light source that comprises: at least one quantum box associated with a discoid wave guide to achieve cylindrical propagation of a wave front emitted by the at least one quantum box in the discoid wave guide; an annular wave guide surrounding the discoid wave guide and having a grating coupler formed on its internal periphery to receive the wave front in normal incidence; an output wave guide optically coupled to the annular wave guide, in which the wave front is guided. The invention includes the method of fabrication of such a source, and its use for emission of a sequence of single photons.

A guided light source that comprises: at least one quantum box associated with a discoid wave guide to achieve cylindrical propagation of a wave front emitted by the at least one quantum box in the discoid wave guide; an annular wave guide surrounding the discoid wave guide and having a grating coupler formed on its internal periphery to receive the wave front in normal incidence; an output wave guide optically coupled to the annular wave guide, in which the wave front is guided. The invention includes the method of fabrication of such a source, and its use for emission of a sequence of single photons.

The visual detection of a silicon optical circuit in a conventional technique depends on sensory decision by a human who visually conducts checking, and there has been limitation in completely detecting small flaws. The optical circuit of the present invention includes, in addition to an optical circuit that implements desired functions, an optical waveguide for flaw detection which surrounds the entire optical circuit and which is sufficiently proximate to the optical waveguide of the optical circuit and grating couplers connected to the optical waveguide for detection. Based on the transmission characteristic measurement of the optical waveguide for detection using the grating couplers, a flaw within each chip can be efficiently discovered in the state of a wafer before being cut into chips. A flaw can also be discovered hierarchically by providing individual optical waveguides for detection for respective chips and by further forming one common optical waveguide for detection over the plurality of chips.

The visual detection of a silicon optical circuit in a conventional technique depends on sensory decision by a human who visually conducts checking, and there has been limitation in completely detecting small flaws. The optical circuit of the present invention includes, in addition to an optical circuit that implements desired functions, an optical waveguide for flaw detection which surrounds the entire optical circuit and which is sufficiently proximate to the optical waveguide of the optical circuit and grating couplers connected to the optical waveguide for detection. Based on the transmission characteristic measurement of the optical waveguide for detection using the grating couplers, a flaw within each chip can be efficiently discovered in the state of a wafer before being cut into chips. A flaw can also be discovered hierarchically by providing individual optical waveguides for detection for respective chips and by further forming one common optical waveguide for detection over the plurality of chips.

Resonant-cavity infrared photodetector (RCID) devices that include a thin absorber layer contained entirely within the resonant cavity. In some embodiments, the absorber is a single type-II InAsGaSb interface situated between an AlSb/InAs superlattice n-type region and a p-type AlSb/GaSb region. In other embodiments, the absorber region comprises quantum wells formed on an upper surface of the n-type region. In other embodiments, the absorber region comprises a W-structured quantum well situated between two barrier layers, the W-structured quantum well comprising a hole quantum well sandwiched between two electron quantum wells. In other embodiments, the RCID includes a thin absorber region and an nBn or pBp active core within a resonant cavity. In some embodiments, the RCID is configured to absorb incident light propagating in the direction of the epitaxial growth of the RCID structure, while in other embodiments, it absorbs light propagating in the epitaxial plane of the structure.

Resonant-cavity infrared photodetector (RCID) devices that include a thin absorber layer contained entirely within the resonant cavity. In some embodiments, the absorber is a single type-II InAsGaSb interface situated between an AlSb/InAs superlattice n-type region and a p-type AlSb/GaSb region. In other embodiments, the absorber region comprises quantum wells formed on an upper surface of the n-type region. In other embodiments, the absorber region comprises a W-structured quantum well situated between two barrier layers, the W-structured quantum well comprising a hole quantum well sandwiched between two electron quantum wells. In other embodiments, the RCID includes a thin absorber region and an nBn or pBp active core within a resonant cavity. In some embodiments, the RCID is configured to absorb incident light propagating in the direction of the epitaxial growth of the RCID structure, while in other embodiments, it absorbs light propagating in the epitaxial plane of the structure.

An optical component comprising at least one first waveguide having a first core and a casing surrounding the first core, and comprising at least one second waveguide having a second core, wherein the first core and the second core are guided adjacent and at a distance to one another in a longitudinal section, and at least one Bragg grating is arranged in said longitudinal section, and at least the first core, the first casing the second core and the Bragg grating are arranged in a single substrate.