Emmanuel S Desurvire

48158046, Mar 28, 1989

Nov 20, 1987

7/123123

Emmanuel Desurvire - Menlo Park CA
Michel J. F. Digonnet - Palo Alto CA
H. J. Shaw - Stanford CA

The Board of Trustees of the Leland Stanford Junior University - Stanford CA

G02B 626
G11C 2100
H04B 900

350 9615

A fiber optic recirculating memory comprises a splice-free length of optical fiber which forms a loop that is optically closed by means of a fiber optic coupler. The coupler couples an optical signal input pulse to the loop for circulation therein, and outputs a portion of the signal pulse on each circulation to provide a series of output pulses. A pump source is included to pump the fiber loop with a pump signal having sufficient intensity to cause stimulated Raman scattering in the fiber loop, and thereby cause amplification of the circulating signal pulse. The fiber characteristics, coupler characteristics, and pump power are selected to yield a Raman gain which compensates for the total round-trip losses in the fiber loop, so as to provide an output pulse train of constant amplitude pulses. The invention may be implemented utilizing either a standard coupler or a multiplexing coupler. The multiplexing coupler advantageously permits independent selection of the coupling ratios for the pump signal and signal pulse, thereby allowing these coupling ratios to be selected for minimum loop loss and maximum pumping efficiency.

50051750, Apr 2, 1991

Nov 27, 1989

7/441495

Emmanuel Desurvire - Middletown NJ
Clinton R. Giles - Middletown NJ
Jay R. Simpson - Fanwood NJ
John L. Zyskind - Shrewsbury NJ

AT&T Bell Laboratories - Murray Hill NJ

G02B 600
H01S 300

372 6

This invention is a rare earth doped optical amplifier with increased gain and lowered pump thresholds. The amplifying scheme is based on a 3 level lasing system rather than the more prevalent 4 level lasing system. Additionally, the transmission mode of the optical fiber at the pump wavelength has a radius which is substantially equal to or greater than the radius of the distribution profile of the rare earth ions in the fiber amplifier core. With the inventive amplifier, a gain of 37 dB and a saturation power of 11. 3 dBm has been obtained with only 54 mW of launch power at. lambda. =1. 49. mu. m.

50270796, Jun 25, 1991

Jul 31, 1990

7/560664

Emmanuel Desurvire - Middletown NJ
Clinton R. Giles - Holmdel NJ
John L. Zyskind - Shrewsbury NJ

AT&T Bell Laboratories - Murray Hill NJ

H01S 330
G02B 626

330 43

This invention relates to an Erbium doped fiber amplifier having improved operating characteristics. Parameters which determine the operating characteristics of an erbium doped fiber amplifier are the concentration of erbium in the core of a fiber; the ratio of the radius of the core of the fiber doped with erbium relative to the radius of the core of the fiber, and, the length of the fiber. It is now recognized that improved fiber amplifier performance can be obtained by varying the core-cladding refractive index difference of the fiber. The various parameters are here defined for providing an erbium doped fiber amplifier having optimum gain characteristics.

47084219, Nov 24, 1987

Feb 8, 1985

6/699853

Emmanuel Desurvire - Menlo Park CA
Michel J. F. Digonnet - Palo Alto CA
H. J. Shaw - Stanford CA

The Board of Trustees of the Leland Stanford Junior University - Stanford CA

G02B 5172

350 9615

A fiber optic recirculating memory comprises a splice-free length of optical fiber which forms a loop that is optically closed by means of a fiber optic coupler. The coupler couples an optical signal input pulse to the loop for circulation therein, and outputs a portion of the signal pulse on each circulation to provide a series of output pulses. A pump source is included to pump the fiber loop with a pump signal having sufficient intensity to cause stimulated Raman scattering in the fiber loop, and thereby cause amplification of the circulating signal pulse. The fiber characteristics, coupler characteristics, and pump power are selected to yield a Raman gain which compensates for the total round-trip losses in the fiber loop, so as to provide an output pulse train of constant amplitude pulses. The invention may be implemented utilizing either a standard coupler or a multiplexing coupler. The multiplexing coupler advantageously permits independent selection of the coupling ratios for the pump signal and signal pulse, thereby allowing these coupling ratios to be selected for minimum loop loss and maximum pumping efficiency.

47945982, Dec 27, 1988

Jul 18, 1986

6/888170

Emmanuel Desurvire - Menlo Park CA
Herbert J. Shaw - Stanford CA

The Board of Trustees of the Leland Stanford Junior University - Stanford CA

H01S 330

372 3

An all-fiber ring laser has a single, uninterrupted length of single-mode optical fiber that is formed into a loop by using an optical coupler. Pump signal pulses at a first optical wavelength are introduced into one end of the optical fiber. Each pump pulse propagates through the loop formed in the fiber and then exits the fiber. The pump signal pulses excite the molecules of the optical fiber to cause them to go to a higher, unstable energy level. When the molecules return to a lower energy level, photons are emitted at a second optical frequency that has a wavelength that is shifted from the wavelength of the pump signal to form laser signal pulses. The coupler is a multiplexing coupler that has a first coupling ratio at the wavelength of the pump signal and has a second coupling ratio at the wavelength of the emitted optical signal. The first coupling ratio is preferably close to zero and the second coupling coefficient is greater than 0. 5. The laser optical signal recirculates in the loop to stimulate further emission of optical energy at the shifted wavelength in phase with the recirculating optical signal.

51173034, May 26, 1992

Aug 23, 1990

7/571958

Emmanuel Desurvire - Middletown NJ
Clinton R. Giles - Holmdel NJ

AT&T Bell Laboratories - Murray Hill NJ

G02B 626
H01S 220
G02F 100

359341

In a transmission system having concatenated optical amplifiers, gain saturation of the optical amplifiers at any stage is caused by the extraction of power from the amplifier by the ASE and amplification of the signal and of the ASE from previous stages. Three methods of operating transmission systems are classsified as free-running, constant-total power and constant-signal power. Differences in performance of the three systems arise from the propagation of signal power and the buildup of the ASE. It is now disclosed that the buildup of ASE noise in a system of either lumped or distributed concatenated optical amplifers can be limited by operating at least a plurality of the optical amplifers to provide unsaturated gain which is greater than the loss of the system and/or each optical amplifier is operated in its saturated state.

49638327, Oct 16, 1990

Aug 8, 1989

7/390864

Emmanuel Desurvire - Middletown NJ
Randy C. Giles - Middletown NJ
Matthew S. Whalen - Rumson NJ

AT&T Bell Laboratories - Murray Hill NJ

G02B 626
H01S 3094

330 43

This invention is directed toward reducing substantially the loss incurred when two optical fibers of different mode diameters are coupled together. In this invention, the coupling of one fiber to that of another where the fibers are of different mode diameters is not with a tapered fusion, core-to-core splice, but with an evanescent field fiber coupler. Briefly, to achieve amplification of a weak optical signal, an amplifying fiber is inserted into the system at one or a plurality of locations. More specifically, at a desired location, the transmission fiber is severed to provide two sections and the severed sections are transversely coupled to the amplifying fiber. The weak signal from the first section of the transmission fiber is coupled into the amplifying fiber via a first evanescent field type of fiber coupler; and the amplified signal is coupled from the amplifying fiber to the second section of the transmission fiber via a second evanescent field type of fiber coupler. The first evanescent field type of fiber coupler is designed to couple substantially all of the signal energy from the first section of the transmission fiber to the amplifying fiber and to couple substantially none of the laser diode pump signal or energy from the amplifying fiber to the transmission fiber. The second evanescent field type of fiber coupler is designed to couple substantially all of the signal energy in the amplifying fiber to the transmitting fiber and substantially no laser diode pump energy is transferred from the amplifying fiber to the transmission fiber.

47385030, Apr 19, 1988

Feb 12, 1986

6/828782

Emmanuel Desurvire - Menlo Park CA
Michel J. F. Digonnet - Palo Alto CA
Herbert J. Shaw - Stanford CA

The Board of Trustees of the Leland Stanford Junion University - Stanford CA

G02B 5172

350 9615

A fiber optic recirculating memory comprises a splice-free length of optical fiber which forms a loop that is optically closed by means of a fiber optic coupler. The coupler couples an optical signal input pulse to the loop for circulation therein, and outputs a portion of the signal pulse on each circulation to provide a series of output pulses. A pump source is included to pump the fiber loop with a pump signal having sufficient intensity to cause stimulated Raman scattering in the fiber loop, and thereby cause amplification of the circulating signal pulse. The fiber characteristics, coupler characteristics, and a pump power are selected to yield a Raman gain which compensates for the total round-trip losses in the fiber loop, so as to provide an output pulse train of constant amplitude pulses. The invention may be implemented utilizing a standard coupler with a pump signal modulation technique. The pump signal is input to the loop as a series of pulses having a duration and a periodicity chosen to prevent overlap of recirculating pump pulses with input pump pulses until at least two circulations of the loop, which minimizes pump power fluctuations and will therefore enhance output signal stability.