Abstract: Certain material and objects can be characterized by a frequency-dependent absorption, dispersion, and reflection of terahertz transients in signals which pass illuminate the material or object. The present terahertz imaging system analyses that frequency dependence in the time-domain by collecting that transmitted signal propagating through the object and then processing the information contained in those signals for every point or "pixel" on that object. This is a non-invasive imaging technique that is capable of differentiating between different materials, chemical compositions, or environments.

Abstract: An apparatus for, and method of, decreasing a temporal duration of an optical input pulse having an input power spectrum associated therewith, the apparatus and method operative on at least unchirped optical input pulses. The apparatus comprises: (1) a zero-dispersion pulse shaper for receiving the optical input pulse and spectrally spreading the input pulse to produce a spectrally-spread pulse and (2) a modulator array interposed within the zero-dispersion pulse shaper for receiving the spectrally-spread pulse and selectively attenuating a portion of the power spectrum of the spectrally-spread pulse by a predetermined amount to produce a selectively-attenuated spectrally-spread pulse, the zero-dispersion pulse shaper focusing and recombining the selectively-attenuated spectrally-spread pulse to produce an output pulse having a broader power spectrum than the input pulse, the output pulse further having a temporal duration less than the input pulse, regardless of whether the input pulse is chirped.

Abstract: An apparatus and method are disclosed for providing holographic matched filters for application in all-optical holographic processing of ultrahigh-speed optical data. A scaled spatial image of temporal-domain data is provided by a spatial light modulator (SLM). The scaled image of the SLM is read out with a single-mode diode laser and transformed into a wavelength spectrum by a Fourier transform lens. The interference fringe patterns between the spectrum of the scaled spatial data pattern and the reference pattern beam are recorded by a holographic recording medium. Alternatively, the scaled spatial image of the temporal data is fixed in an aperture mask. An apparatus and method are also disclosed for decoding high-speed optical signal packet headers using holographic matched filters.

Abstract: An apparatus and method provides optical multiple wavelength signals using a single optical broadband source to generate many independent optical wavelength channels. An optical transmitter includes a pulse chirping device which separates the frequency components of periodic optical pulses in the time domain forming separate wavelength channels which are separately modulated by a high-speed broadband optical modulator. A receiver includes a passive splitter to separate the individual wavelength channels. The chirped-pulse transmitter can then be conveniently adjusted to provide optimum overlap of wavelength channels with the modulating channel spectra.

Abstract: Certain material and objects can be characterized by a frequency-dependent absorption, dispersion, and reflection of terahertz transients in signals which pass illuminate the material or object. The present terahertz imaging system analyses that frequency dependence in the time-domain by collecting that transmitted signal propagating through the object and then processing the information contained in those signals for every point or "pixel" on that object. This is a non-invasive imaging technique that is capable of differentiating between different materials, chemical compositions, or environments.

Abstract: A serial-to-parallel and parallel-to-serial conversion apparatus and method are disclosed to convert optical pulse data into temporally multiplexed ultra-fast optical pulses, and vice versa, using Fourier holographic transform techniques. In a first embodiment, optical pattern data is converted from a serial temporal-domain optical input signal to an output signal having parallel bits by recording a spectral hologram of the pulse data and reading it out with a continuous-wave (cw) laser. In a second embodiment, signals representing input bits in parallel may be optically multiplexed in the time domain, so that a single optical fiber may carry such signals without the electronic processing necessary in conventional switching multiplexers.

Abstract: The present invention provides an apparatus and method for high-density optical wavelength division multiplexing (WDM) using a single optical source. An optical wavelength division multiplexer in accordance with the present invention includes an optical source providing an optical pulse signal. A wavelength splitter separates the optical pulse signal spectrum into a plurality of channel signals at different wavelengths such that each channel signal may be separately modulated or otherwise processed. A wavelength combiner then recombines the separately modulated channel signals to provide a high-density WDM optical signal particularly well-suited for use in optical circuit interconnection and optical communication network applications. The high-density single-source multiplexer of the present invention may also be conveniently adjusted to align channel signal wavelengths or to compensate for optical fiber dispersion.

Abstract: Amplitude noise is dramatically reduced in an optically pumped modelocked laser arrangement by incorporating an intra-cavity or external cavity mode selection element with a continuous-wave pump laser coupled optically to a modelocked laser. The mode selection element causes a light beam generated from the pump laser to operate nominally at a single frequency, that is, substantially a single longitudinal mode. Mode selection may be realized with an air-spaced or solid material Fabry-Perot etalon.