Abstract: This disclosure provides systems, methods, and apparatus for mitigating the effects of interference signals on optical signals received at a direct-detection optical receivers. The optical receivers are capable of attenuating interference noise signals resulting from the interference between a transmitted optical signal transmitted from a transmitter to the optical receiver and one or more additional signals received at the optical receiver. The interference can be due to multi-path interference or due to in-band interference. The receivers include a tunable filter for filtering the received optical signal to remove the interference. A frequency offset module processes the received optical signal to determine a frequency offset indicative of the difference between the carrier frequencies of a modulated optical signal and an interference optical signal.

Abstract: This disclosure provides systems, methods, and apparatus for mitigating the effects of interference signals on optical signals received at a direct-detection optical receivers. The optical receivers are capable of attenuating interference noise signals resulting from the interference between a transmitted optical signal transmitted from a transmitter to the optical receiver and one or more additional signals received at the optical receiver. The interference can be due to multi-path interference or due to in-band interference. The receivers include a tunable filter for filtering the received optical signal to remove the interference. A frequency offset module processes the received optical signal to determine a frequency offset indicative of the difference between the carrier frequencies of a modulated optical signal and an interference optical signal.

Abstract: This disclosure provides systems, methods, and apparatus for mitigating the effects of interference signals on optical signals received at a direct-detection optical receivers. The optical receivers are capable of attenuating interference noise signals resulting from the interference between a transmitted optical signal transmitted from a transmitter to the optical receiver and one or more additional signals received at the optical receiver. The interference can be due to multi-path interference or due to in-band interference. The receivers include a tunable filter for filtering the received optical signal to remove the interference. A frequency offset module processes the received optical signal to determine a frequency offset indicative of the difference between the carrier frequencies of a modulated optical signal and an interference optical signal.

Abstract: This disclosure provides systems, methods, and apparatus for mitigating the effects of interference signals on optical signals received at a direct-detection optical receivers. The optical receivers are capable of attenuating interference noise signals resulting from the interference between a transmitted optical signal transmitted from a transmitter to the optical receiver and one or more additional signals received at the optical receiver. The interference can be due to multi-path interference or due to in-band interference. The receivers include a tunable filter for filtering the received optical signal to remove the interference. A frequency offset module processes the received optical signal to determine a frequency offset indicative of the difference between the carrier frequencies of a modulated optical signal and an interference optical signal.

Abstract: Systems and methods for reducing temperature of an optical signal source co-packaged with a driver are provided. An optical transmitter can include a housing. The optical transmitter can include an optical signal source positioned within the housing. The optical transmitter can include a signal source driver positioned within the housing and configured to control an output of the optical signal source. The optical transmitter can include a substrate mounted on an interior surface of the housing and having a microwave waveguide coupled to it. The microwave waveguide can be configured to direct electrical signals originating outside the housing to the signal source driver. The substrate is can also be configured to limit heat transfer from the signal source driver to the optical signal source.

Abstract: In some implementations, the output of a directly modulated laser (DML) includes nonlinearities with respect to the input signal driving the DML. When the DML is transmitting an amplitude modulated signal, the nonlinearities can induce noise into the signal, which makes it difficult for a receiving node to correctly decode the received signal. The system and methods described herein pre-correct the error caused by the nonlinearities of the DML by filtering (or pre-correcting) the data signal that drives the DML.

Abstract: The invention relates to a compact transmitter optical sub-assembly (OSA), which can be used in small form factor optical transceivers. To limit back reflections from entering the laser cavity, the laser is disposed on a silicon optical bench (SiOB) at an acute angle to the longitudinal axis of the OSA. A portion of the light from the laser cavity passes through the back end of the laser cavity for measuring by a monitor photodiode. A rear beam steering lens redirects the portion of light into a v-groove in the SiOB and off of a reflective surface formed in the end thereof to the monitor photodiode, which is positioned face down over the v-groove.

Abstract: The present application relates to a Raman amplifier having an increased dynamic range, and particularly for laser pump sources and a method of pumping Raman fiber amplifiers over a greater dynamic range. In a multi-channel optical system, optical amplifiers must be able to provide gains over a large dynamic range, which is determined by the distribution of node-to-node distances in the network, as well as the number of channels. The present invention has found that the dynamic range of a Raman amplifier can be significantly increased by using pulse width modulation to pulse pump current at or near the minimum current stability threshold, in order to produce lower power output. The duty cycle of the pulsed current is selected to achieve a time-averaged operating condition, thus the time averaged pump power can be reduced in a linear fashion well below the capability of a continuous wave system.

Abstract: The invention relates to a method for automatic dynamic gain control in optical Raman amplifiers and an optical Raman amplifier adapted for the same. The present invention has found that in multiple pump Raman amplifiers a substantially linear relationship exists between total amplified signal power and pump power for each of different wavelength pumps, in order to maintain an original gain profile and gain levels for an optical link with a fully loaded channel configuration, in response to dropped channels. In accordance with the method, and an amplifier programmed to practice the method, a set of pump power values and signal level values required to maintain the characterized gain profile and gain levels for a plurality of channel loading configurations are pre-established for the each pump wavelength. A linear function from each set of pre-established values is derived for each pump wavelength.

Abstract: The invention relates to a compact transmitter optical sub-assembly (OSA), which can be used in small form factor optical transceivers. To limit back reflections from entering the laser cavity, the laser is disposed on a silicon optical bench (SiOB) at an acute angle to the longitudinal axis of the OSA. A portion of the light from the laser cavity passes through the back end of the laser cavity for measuring by a monitor photodiode. A rear beam steering lens redirects the portion of light into a v-groove in the SiOB and off of a reflective surface formed in the end thereof to the monitor photodiode, which is positioned face down over the v-groove.

Abstract: The invention relates to a method for automatic dynamic gain control in optical Raman amplifiers and an optical Raman amplifier adapted for the same. The present invention has found that in multiple pump Raman amplifiers a substantially linear relationship exists between total amplified signal power and pump power for each of different wavelength pumps, in order to maintain an original gain profile and gain levels for an optical link with a fully loaded channel configuration, in response to dropped channels. In accordance with the method, and an amplifier programmed to practice the method, a set of pump power values and signal level values required to maintain the characterized gain profile and gain levels for a plurality of channel loading configurations are pre-established for the each pump wavelength. A linear function from each set of pre-established values is derived for each pump wavelength.

Abstract: The present application relates to a Raman amplifier having an increased dynamic range, and particularly for laser pump sources and a method of pumping Raman fiber amplifiers over a greater dynamic range. In a multi-channel optical system, optical amplifiers must be able to provide gains over a large dynamic range, which is determined by the distribution of node-to-node distances in the network, as well as the number of channels. The present invention has found that the dynamic range of a Raman amplifier can be significantly increased by using pulse width modulation to pulse pump current at or near the minimum current stability threshold, in order to produce lower power output. The duty cycle of the pulsed current is selected to achieve a time-averaged operating condition, thus the time averaged pump power can be reduced in a linear fashion well below the capability of a continuous wave system.

Abstract: A tunneling ferrimagnetic magnetoresistive sensor that has a .DELTA.R/R greater than that of known magnetoresistive sensors, and that, with appropriate electrode materials, can undergo a substantial change in resistance in response to a magnetic field in the intensity range of 10s of Oe, which is typical of the intensity of the magnetic fields encountered in magnetic recording media such as discs and tapes. The tunneling ferrimagnetic magnetoresistive sensor is composed of a stack of thin-film layers that include a layer of a ferrimagnetic material, a layer of a magnetic material, and a layer of an insulator interposed between the layer of the ferrimagnetic material and the layer of the magnetic material. The ferrimagnetic material is conductive. The magnetic material is also conductive and has a coercivity substantially different from that of the ferrimagnetic material.