Abstract: An optical amplifier includes at least one amplification stage having a saturation recovery time of less than one (1) millisecond. The amplification stage includes a gain medium operable to receive at least one pump signal and to receive from a multiple span communication link an optical signal comprising a leading edge. The at least one pump signal and the optical signal travel in the same direction at approximately the same speed through at least a portion of the gain medium. In one particular embodiment the leading edge of the optical signal after passing through a plurality of amplifiers when received by a receiver coupled to the communication link comprises a peak power that is no more than ten times the average power of the optical signal at the receiver.

Abstract: An acoustic isolator for attenuating through-tool acoustic signals comprises a plurality of u-shaped link members, where each link member has two sets of ears. A plurality of yoke members are adapted to fit between cooperating sets of ears. A plurality of pins connect the plurality of u-shaped link members to the plurality of yoke members for providing limited flexural compliance. The isolator may be made from metallic and/or composite materials.

Abstract: An all fiber optical filter is formed by stretching an optical fiber. The all fiber filter includes a core, an inner cladding, and an outer cladding. A core index of refraction is greater than an outer cladding index of refraction. The outer cladding index of refraction is greater than an inner cladding index of refraction. The all fiber optical filter attenuates a portion of an optical signal by transferring optical energy from the core to the outer cladding by evanescent coupling. The all fiber optical filter has a compact structure, which prevents bending and provides stable temperature performance. The all fiber optical filter is preferably used in Wavelength Division Multiplexing (WDM) systems for gain flattening of gain responses from Erbium Doped Fiber Amplifiers (EDFAs). Alternatively, the all fiber optical filter is used in other applications where optical filtering or attenuation is needed.

Abstract: A bidirectional WDM optical system in which crosstalk between interleaved channels of different wavelengths is suppressed by the inclusion in the amplifier gain block of four-port filters that discriminate on the basis of the wavelength of the interleaved signals passing through the four port filters.

Abstract: Methods and apparatus are disclosed for an intrusion detection system for secure fiber optic communication systems. A guard signal is transmitted over the optical fiber communication link and both the modal power and modal phase delay of this signal are monitored. Intrusions into the link for the purpose of intercepting information being transmitted, cause changes in the modal phase delay and power of the guard signal. These changes, when detected by the monitoring system, indicate the presence of an intruder. A fiber profile which is optimal for both transmission and intrusion detection purposes is described.

Abstract: A fiber optic transmission system with low cost transmitter compensation includes an electro-absorption modulated laser operable to generate an optical signal for transmission over a fiber optic communication link. The system further includes a Raman amplifier stage coupled to the communication link, the Raman amplifier stage having a gain medium including a dispersion compensating fiber. The dispersion compensating fiber is operable to at least partially compensate for a distortion caused by the electro-absorption modulated laser. The Raman amplifier stage is operable to at least partially compensate for a loss associated with the dispersion compensation fiber.

Abstract: The present invention relates to a method for estimating the position and trajectory of a drill during drilling of boreholes in rock. The method comprising the steps of determining the starting position of the drill bit and recording the received transient seismic waves generated by the drill on impact, and estimating the difference in arrival time between events. From these, the relative distances, between the positions of the drill bit at different events are calculated and from these the present position is calculated.

Abstract: A processor that utilizes the presence of harmonic components in a noisy signal environment to enhance the desired frequency spectrum of the signal. Received signal and noise are filtered to separate the harmonic components of the signal. These harmonic components are then combined in a prescribed manner to form a multiplicity of combined signals with varying harmonic content. The combined signals are then further processed to establish a signal detection.

Abstract: An apparatus and method are described for exploiting almost the full almost 25TH% of bandwidth available in the low-loss window in optical fibers (from 1430 nm-1620 nm) using a parallel combination of optical amplifiers. The low-loss window at about 1530 nm-1620 nm can be amplified using erbium-doped fiber amplifiers (EDFAs). However, due to the inherent absorption of the erbium at shorter wavelengths, EDFAs cannot be used below about 1525 nm without a significant degradation in performance. For the low-loss window at approximately 1430-1530 nm, amplifiers based on nonlinear polarization in optical fibers can be used effectively. A broadband nonlinear polarization amplifier (NLPA) is disclosed which combines cascaded Raman amplification with parametric amplification or four-wave mixing. In particular, one of the intermediate cascade Raman order wavelengths &lgr;r should lie in close proximity to the zero-dispersion wavelength &lgr;0 of the amplifying fiber.

Abstract: A semiconductor optical amplifier includes (a) a single-mode waveguide region which provides a single-mode to a guided light-wave, (b) a first multi-mode interference waveguide region which has a greater waveguide width than that of the single-mode waveguide region, is optically connected to the single-mode waveguide region, and provides a mode including a multi-mode, to the guided light-wave, and (c) a second multi-mode interference waveguide region which has a greater waveguide width than that of the first multi-mode interference waveguide region, is optically connected to the first multi-mode interference waveguide region, and provides a mode including a multi-mode, to the guided light-wave.

Abstract: An optical preamplifier with an amplification unit is for amplifying an optical signal and compensating dispersion of the optical signal after receiving the optical signal from an optical transmitter, and thereof for supplying the optical signal to an optical receiver.

Abstract: A method and apparatus for detecting if an optical module has been disconnected from a fiber span or if there has been a break in the span, and for automatically reducing the output signal level of the optical module such that the output signal level is within an acceptable safety limit. Also disclosed is a system and technique for automatically resetting a Raman pump unit once the source of an optical leak has been located and addressed.

Abstract: The present invention provides a Raman amplification pumping module and others with a structure for effectively suppressing degradation of quality of signal light even with a breakdown in either one of a plurality of light sources. The Raman amplification pumping module is provided with light sources for emitting respective lightwaves with center wavelengths different from each other, and each of the center wavelengths of the lightwaves from these light sources is adjusted so that a difference between two center wavelengths selected therefrom is less than 6 nm.

Abstract: A short pulse laser system uses dispersive optics in a chirped-beam amplification architecture to produce high peak power pulses and high peak intensities without the potential for intensity dependent damage to downstream optical components after amplification.

Abstract: The present invention is related to an all-optical OR device embodied by using the gain saturation and wavelength conversion characteristics of semiconductor optical amplifier (SOA), and more particularly, to a technique to embody an all-optical OR gate that performs all-optical logic operation by utilizing optical signals transmitted at arbitrary points of optical circuits such as optical computing circuits as the pump signal and the probe signal.

Abstract: A seismic signal is represented as a combination of a geologic signal and a noise signal. The representation of the seismic signal is decomposed into a linear combination of orthonormal components. One or more components are identified in which the geologic signal and the noise signal are uncorrelated. The noise signal is expanded as a product of an unknown noise amplitude modulation signal and a known noise spatial periodicity signal at the identified components. The expansion is solved for an estimate of the noise amplitude modulation signal at the identified components. The noise signal is estimated by multiplying the estimated noise amplitude modulation signal by the noise spatial periodicity signal. The estimated noise signal can be removed from the seismic signal to generate an estimate of the geologic signal.

Abstract: The present invention relates to an implementation method of all-optical half adder by using semiconductor optical amplifier(SOA)-based devices and the apparatus thereof. In more detail, it relates to an implementation method of all-optical half adder comprising an all-optical XOR gate and an all-optical AND gate, implemented by using SOA-based devices, and an apparatus thereof.

Abstract: Semiconductor optical amplifier with polarization independent gain. A polarization adjusting layer is formed on a semiconductor optical amplifier. The semiconductor optical amplifier has an active region that includes both compressively strained and tensile strained quantum wells. The polarization adjusting layer is formed and then etched to a thickness that repositions an optical signal within the active region such that the gain of the optical signal is independent of the polarization of the optical signal.

Abstract: A Raman pump unit for connection to a main optical path includes a signal generator for generating a plurality of at least partially complementary dither signals, a plurality of modulators connected to said signal generator capable of receiving pump driver signals and modulating these in accordance with the dither signals and a plurality of pumps connected to the modulators for receiving producing optical pump signals from the modulated pump driver signals. The unit also includes an optical coupler connected to the plurality of pumps for introducing a combination of the optical pump signals into the main optical path. The use of pump dithering increases the spectral width of the optical pump signals being injected into the main optical path, which helps to fight the deleterious effects of SBS. Meanwhile, pump noise transfer to the main optical signal is mitigated because the signal gain is the combination of two at least partially complementary pump dither signals.

Abstract: A method of performing normal moveout (NMO) correction and stacking of a common-midpoint (CMP) gather of seismic traces in a manner that avoids NMO stretch is disclosed. A CMP gather without NMO correction is modeled as the sum of a series of short overlapping time intervals whose center times follow the NMO curve as it changes with offset. The sample values contained in these intervals are solved simultaneously by performing a statistical fit to the CMP gather based on this model. A CMP stacked trace is formed by summing these intervals at their zero-offset positions at each time sample.