Julius A Goldhar

6335819, Jan 1, 2002

Feb 18, 2000

09/506745

Pak S. Cho - Gaithersburg MD
Julius Goldhar - Silver Spring MD
Daniel Mahgerefteh - Los Angeles CA

University of Maryland - Riverdale MD

H01S 300

359333, 359176

The present invention provides simultaneous all-optical regeneration (re-shape and re-amplify) and wavelength conversion using a reverse-biased electroabsorption modulator. The nonlinear optical transmission characteristic of the electroabsorption modulator reshapes the degraded input data by selective absorption of the optical noise and, therefore, increases the signal-to-noise ratio of the output. Reverse biasing the modulator allows fast recovery of the optical absorption for high data-rate operation without the detrimental bit-patterning effect. Error-free wavelength conversion and regeneration at 20 Gb/s was obtained with more than 3-dB improvement of the receiver sensitivity at a bit-error-rate of 10. Embodiments and applications of the present invention include an all-optical SEAM regenerator, an all-optical distributed feedback laser SEAM (DFB-SEAM) regenerator, an all-optical SEAM with fiber Bragg grating (SEAM-FBG) regenerator, an all-optical SEAM with polarizing beam splitter (SEAM-PBS) regenerator, an all-optical Mach-Zehnder interferometric (MZI-SEAM) regenerator, an all-optical 3-port MZI-SEAM regenerator, and a SEAM-based optimized receiver.

6701049, Mar 2, 2004

Mar 21, 2003

10/249201

Ehab Awad - Hyattsville MD
Julius Goldhar - Silver Spring MD
Pak Shing Cho - Gaithersburg MD
Christopher Richardson - Columbia MD
Norman Moulton - Ellicott City MD

The United States of America as represented by The National Security Agency - Washington DC

G02F 135

385122, 398141, 398155

All-optical timing extraction and optical clock recovery for high-speed return-to-zero binary optical data streams using the timing difference between clock and data counter-propagating optical pulses in a non-linear optical waveguide where the first pulse to arrive at the non-linear optical waveguide partially saturates the transmission properties of the waveguide resulting in a change of the transmission properties seen by the lagging pulse. A balanced photo-detector makes delay-dependent comparisons of the clock and data pulses peak power and generates an error signal used in a phase-locked loop configuration to synchronize the clock to the data stream.

60813237, Jun 27, 2000

Feb 19, 1998

9/026429

Daniel Mahgerefteh - Washington DC
Julius Goldhar - Silver Spring MD
Douglas Llewellyn Butler - Painted Post NY
Lance Gregory Joneckis - Severna Park MD

The United States of America as represented by the Director of the
National Security Agency - Washington DC

G01N 2100

356 731

An apparatus and method for measuring the spectral dependence of the Raman gain coefficient in optical fibers is presented. This approach measures the power level of Raman scattering in both a walk-off limited region and a physical fiber length limited region and, from these measurements, extracts the spectral dependence of the Raman gain coefficient. Access to these two regions is accomplished through control of the excitation pulse temporal width and relies on fiber dispersion to separate the excitation light from the Raman scattered light for short pulse widths. This approach measures the spectral dependence of the Raman gain without the necessity of absolute power measurement of the Raman scattered light, the need for a reference standard, or the need of a frequency tunable secondary optical source.

43085075, Dec 29, 1981

Dec 11, 1979

6/102470

Lyn D. Pleasance - Livermore CA
John R. Murray - Danville CA
Julius Goldhar - Walnut Creek CA
Laird P. Bradley - Livermore CA

The United States of America as represented by the United States
Department of Energy - Washington DC

H01S 309

331 945G

Method and apparatus for electrical excitation of a laser gas by application of a pulsed voltage across the gas, followed by passage of a pulsed, high energy electron beam through the gas to initiate a discharge suitable for laser excitation. This method improves upon current power conditioning techniques and is especially useful for driving rare gas halide lasers at high repetition rates.

46155880, Oct 7, 1986

Oct 19, 1984

6/662641

Julius Goldhar - San Ramon CA
Mark A. Henesian - Livermore CA

The United States of America as represented by the United States
Department of Energy - Washington DC

G02F 103
H01J 1500

350392

A low pressure gas electrode utilizing ionized gas in a glow discharge regime forms a transparent electrode for electro-optical switches. The transparent electrode comprises a low pressure gas region on both sides of the crystal. When the gas is ionized, e. g. , by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the electrode is a transparent electrode. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. The plasma can be created either by the main high voltage pulser used to charge up the crystal or by auxiliary discharges or external sources of ionization. A typical configuration utilizes 10 torr argon in the discharge region adjacent to each crystal face.