Montana State University

S2 Corporation

The Research and Development Intstitute

Kristian D Merkel

William Randall Babbitt

Krishna Rupavatharam

Tiejun Chang

Randy Ray Reibel

Colton Richard Stiffler

Zachary Cole

Charles W Thiel

Scott Henry Bekker

Mingzhen Tian

Zeb William Barber

Peter B Sellin

Randy W Equall

Kelvin Wagner

Mark Allen Neifeld

Alex Woidtke

Rufus Cone

Calvin Harrington

Aaron Traxinger

Todd Harris

A method and apparatus includes an optical source for a single order single-sideband suppressed-carrier optical signal with a bandwidth that scales from over 4 gigaHertz or is at least 8 GHz from an optical carrier frequency. In an example embodiment, an apparatus includes a stable laser source configured to output an optical carrier signal at a carrier frequency. The apparatus includes a radio frequency electrical source configured to output an electrical radio frequency signal with a radio frequency bandwidth less than one octave. The apparatus also includes an optical modulator configured to output an optical signal with the optical carrier signal modulated by the radio frequency signal in a plurality of orders (harmonics) of optical frequency sidebands. The apparatus further includes an optical filter configured to pass one single order optical frequency sideband of the optical signal, which sideband does not overlap the sideband of any other harmonic.

Techniques for single sideband suppressed carrier (SSBSC) optical signals

A method and apparatus includes an optical source for a single order single-sideband suppressed-carrier optical signal with a bandwidth that scales from over 1 gigaHertz to greater than 20 gigaHertz. In an example embodiment, an apparatus includes a stable laser source configured to output an optical carrier signal at a carrier frequency. The apparatus includes a radio frequency electrical source configured to output an electrical radio frequency signal with a radio frequency bandwidth less than one octave. The apparatus also includes an optical modulator configured to output an optical signal with the optical carrier signal modulated by the radio frequency signal in a plurality of orders of optical frequency sidebands. The apparatus further includes an optical filter configured to pass one single order optical frequency sideband of the optical signal.

Techniques for single sideband suppressed carrier (SSBSC) optical signals that scale to bandwidths over 20 gigahertz

Techniques for spatial spectral holography include a doped crystal comprising Thulium doped into a host crystal of Yttrium Lutetium Aluminum Garnet wherein a concentration of Thulium atoms is less than 3 atomic percent. Techniques further include an apparatus with a source for optical electromagnetic radiation and a cryocooler configured to maintain an operating temperature in a range from about 3 Kelvin to about 6 Kelvin. The cryocooler includes a first optical window. The apparatus also includes a doped crystal comprising Thulium doped into a host crystal of Yttrium Lutetium Aluminum Garnet disposed inside the cryocooler in a position to be illuminated by incident optical electromagnetic radiation derived from the source. The apparatus also includes a detector configured to detect optical electromagnetic radiation emitted from the doped crystal. Techniques include a method for using at least one of the above doped crystals.

Techniques for spatial spectral holography

A method and apparatus for producing an arbitrary broadband waveform includes generating a first narrowband waveform and generating a frequency-shifted replica by frequency shifting the first narrowband waveform by a frequency shift. A second narrowband waveform is also generated. A broadband waveform is generated by combining the frequency-shifted replica and the second narrowband waveform.

Methods and apparatus for photonic arbitrary waveform generation over wide-bandwidth and extended time apertures

A method and apparatus for converting an analog waveform to a series of digital values includes receiving an input analog waveform to be digitized over a particular frequency band. A phase-sensitive frequency-domain representation of the input analog waveform is recorded. The phase-sensitive frequency-domain representation is read out and digitized to produce a spectral series of digital values. An output series of digital values that represent the analog waveform digitized over the particular frequency band is determined based on the spectral series. In some embodiments, the spectral series of digital values is produced with a conventional high dynamic range, low bandwidth digitizer that has a bandwidth at least a factor of two less than a width of the particular frequency band for digitizing the target analog waveform.

Broadband analog to digital conversion using analog spectral recording

Techniques for producing an optical broadband frequency sweep or chirp, include generating a narrowband frequency chirp and a frequency-shifted replica. The narrowband chirp has an optical carrier frequency, a pulse duration and a pulse bandwidth. A frequency-shifted replica is generated by frequency shifting the narrowband chirp by a frequency shift. Adding the frequency-shifted replica after a start of the narrowband chirp by a delay generates a broadband frequency chirp. Alternatively, the frequency-shifted replica is generated by frequency shifting a constant frequency pulse, and modulating the frequency-shifted pulse to generate narrowband chirps that are added to form the broadband chirp.

Method and apparatus for optical broadband frequency chirp

Techniques for detecting optical spectral properties of a target are described. The technique includes providing an optical carrier which has an optical frequency bandwidth which is narrow compared to the width of the narrowest spectral feature of the target to be determined. This optical carrier is then electro-optically modulated with an RF frequency chirp, creating an optical chirp probe beam with a frequency chirped optical spectrum having upper and lower frequency chirped sidebands that have amplitudes sufficient to be detected at a detector. The sidebands are frequency bands arranged symmetrically around the optical carrier frequency. The attributes of a sideband include a start frequency, bandwidth and chirp rate. A probe beam is generated with the sidebands and directed onto a target having a physical property with optical frequency dependence. An optical response signal resulting from an interaction between the probe beam and the target is detected. The optical frequency dependence of the physical property of the target is determined based on the optical response signal and the attributes of the sidebands.

Method and apparatus for detecting optical spectral properties using optical probe beams with multiple sidebands

Techniques for reconfiguring spectral features stored in a medium based on a two-state atomic system with transition dipole moment &#x3bc; includes causing a chirp to pass into the medium. The chirp includes a monochromatic frequency that varies in time by a chirp rate &#x3ba; over a frequency band Bduring a time interval T. The amplitude Aof the chirp is constant over Band equal to=(bar/&#x3bc;&#x3c0;)&#x221a;{square root over ((&#x3ba; ln [2/&#x3b5;]))},The term hbar is reduced Plank's constant, ln is a natural logarithm function, and &#x3c0; is a ratio of a circumference of a circle to a diameter of the circle. For &#x3b5;&#x3c;&#x3c;1, the atomic-state populations in the two states are inverted. For &#x3b5;=1, prior atomic-state populations are erased, with final populations equal in the two states, regardless of populations before erasure.

Techniques for using chirped fields to reconfigure a medium that stores spectral features

Techniques for analog processing of high time-bandwidth-product (TBP) signals use a material with an inhomogeneously broadened absorption spectrum including multiple homogeneously broadened absorption lines. A first set of signals on optical carriers interact in the material during a time on the order of a phase coherence time of the homogeneously broadened absorption lines to record an analog interaction absorption spectrum. Within a time on the order of a population recovery time for a population of optical absorbers it the material, the interaction absorption spectrum in the material is read to produce a digital readout signal. The readout signal represents a temporal map of the interaction absorption spectrum, and includes frequency components that relate to a processing result of processing the first set of signals. The techniques allow processing of RADAR signals for improved range resolution to a target, as well as speed of the target, among other uses.

Method and apparatus for processing high time-bandwidth signals using a material with inhomogeneously broadened absorption spectrum

Techniques for reading the spectral content of a spatial-spectral grating in an inhomogeneously broadened transition (IBT) material include directing multiple probe waveforms to probe a spatial mode of the IBT material. Each probe waveform is a linear frequency modulated chirp; each probe waveform partially overlaps in frequency with a different probe waveform; and multiple output signals are detected from the IBT material in response. Based on the multiple output signals, a readout signal is determined that represents a complete or nearly complete temporal map of the spectral content of the spatial-spectral grating. Calibration of the frequency content can be achieved by simultaneously reading out calibration spectral features. These techniques allow high-bandwidth spectral content to be read with segmented narrow bandwidth chirp probe waveforms and low-bandwidth high-dynamic-range detectors and digitizers.

Techniques for multiple frequency chirp readout of material with inhomogeneously broadened absorption spectrum

Techniques for recovering optical spectral features include receiving a detected time series that represents a temporally varying intensity of an optical signal. The optical signal is formed in response to an interaction between a target optical spectrum and a chirped optical field. The chirped optical field is an optical field that has a monochromatic frequency that varies in time. The target optical spectrum is an optical frequency dependent optical property of a material or device. A phase correction factor is determined based only on one or more properties of the chirped optical field. The detected time series is corrected based on the phase correction factor to produce an output time series that reproduces in time a shape of the target spectrum in frequency. These techniques allow for fast measurement of spectral features and eliminate the need for prior knowledge of the target optical spectrum to adjust the chirp rate.

Techniques for recovering optical spectral features using a chirped optical field

Techniques for continuously programming a coherent transient spatial-spectral optical signal processor involve the repeated application of two or more spatially distinct optical programming pulses to a non-persistent hole-burning material to write an accumulated, spatial-spectral population grating with low intensity optical pulses as compared to single shot programming. An optical data stream is introduced on a processing beam, resulting in a processor output signal spatially distinct from all the processing pulses. Programming and processing take place simultaneously, asynchronously and continuously. For accumulated gratings, the frequency stability of the optical source is an important consideration. Assuming a sufficiently stable optical source, simulations show that an accumulated (and maintained) grating in steady state, for both storage of a true-time delay and/or pattern waveform, can be highly efficient using currently available materials, on the order of that predicted for a perfect photon-gated device. An experimental demonstration of the continuous programming concept for true time delays programmed with chirped pulses is presented, showing the accumulation of the grating with low area pulses over time until it reaches steady state, for times longer than the persistence of the material.

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Bozeman, MT, United States of America

Kristian D Merkel