Abstract: A dual-hop system for optical wireless communication between a base station on Earth and satellite is described. The system includes a first Thulium-Doped Fiber Amplifier (TDFA) at the base station and a second TDFS installed in a High-Altitude Platform Station (HAPS). The first TDF A includes a first thulium-doped fiber (TDF) and a first set of optical pumps. The first TDFA amplifies an input optical signal for wireless transmission to the HAPS installed at a specific altitude. The amplified signal is received by the second TDFA at HAPS. The second TDFA includes a second TDF and a second set of optical pumps. The signal amplified by the second TDFA is compensated for attenuation before it is wirelessly transmitted to the satellite. Both TDFAs ensure that the amplification of the optical signals, either through power amplification or gain, meets specified criteria to maintain the integrity and quality of the transmitted signals.

Abstract: A multiwavelength erbium-doped fiber laser (EDFL) including a single ring cavity, a wave division multiplexer (WDM) coupler, and a pump laser. The pump laser injects a pump laser beam into the single ring cavity. The multiwavelength EDFL includes an erbium doped fiber, an optical isolator (ISO), and a fiber coupler. The erbium doped fiber amplifies the pump laser beam and generates an amplified laser beam. The fiber coupler divides the amplified laser beam into an output laser beam and a laser beam retained in the single ring cavity. The multiwavelength EDFL includes a tunable optical filter (TOF) and an out of cavity comb filter (CF) having a dual-drive Mach-Zehnder modulator (DD-MZM). The TOF receives the laser beam retained in the single ring cavity and filter the retained laser beam to a desired wavelength. The DD-MZM receives the output laser beam and divides the output laser beam into multiple wavelengths.

Abstract: The present invention describes a free spectral range (FSR) and center wavelength tunable redundant optical comb based on a sagnac loop mirror (SLM) and bidirectional Mach-Zehnder modulator (BMZM). The optical signal from a continuous wave (CW) laser is split into two parts which travel in clockwise and counter clockwise directions inside the SLM and are modulated by sinusoidal RF signal with the help of BMZM. The modulation of optical signals with sinusoidal RF signal using BMZM results into the generation of two optical combs inside the SLM. Both optical combs are obtained simultaneously at the output port of the SLM when the polarization controller (PC) is adjusted to have 90° phase difference between the clockwise and counterclockwise generated combs. The proposed design can be used in protection switching and in data centers. A corresponding method for generating redundant optical combs is also provided.

Abstract: A Holmium-doped fiber amplifier (HDFA) with cascaded pumping is disclosed. The cascaded pumping has at least two pumping stages arranged so that an emission spectrum of a preceding pumping stage at least partly corresponds to an absorption spectrum of the succeeding pumping stage, and the pumping stages are staggered so that an emission spectrum of the last pumping stage at least partly corresponds to an absorption spectrum of the Holmium-doped fiber.

Abstract: A system and method for in-service optical dispersion determination are provided. Optical dispersion is determined by splitting a first optical signal into two components, introducing a time delay between the two components such that corresponding pulses of the two components partially overlap, combining the two components to generate a combined optical signal comprising a first component and a second component, determining power of the combined optical signal while applying a plurality of dispersion compensation values, in order to determine a dispersion compensation value that results in a minimum detected power of the combined optical signal. Polarization Mode Dispersion is determined by adjusting the time delay that is introduced until the power of the combined optical signal is substantially equal for all of the plurality of dispersion compensation values.

Abstract: A system and method for in-service optical dispersion determination are provided. Optical dispersion is determined by splitting a first optical signal into two components, introducing a time delay between the two components such that corresponding pulses of the two components partially overlap, combining the two components to generate a combined optical signal comprising a first component and a second component, determining power of the combined optical signal while applying a plurality of dispersion compensation values, in order to determine a dispersion compensation value that results in a minimum detected power of the combined optical signal. Polarization Mode Dispersion is determined by adjusting the time delay that is introduced until the power of the combined optical signal is substantially equal for all of the plurality of dispersion compensation values.

Abstract: A system and method for in-service optical dispersion determination are provided. Optical dispersion is determined by splitting a first optical signal into two components, introducing a time delay between the two components such that corresponding pulses of the two components partially overlap, combining the two components to generate a combined optical signal comprising a first component and a second component, determining power of the combined optical signal while applying a plurality of dispersion compensation values, in order to determine a dispersion compensation value that results in a minimum detected power of the combined optical signal. Polarization Mode Dispersion is determined by adjusting the time delay that is introduced until the power of the combined optical signal is substantially equal for all of the plurality of dispersion compensation values.

Abstract: A dynamic dispersion compensation system and method are provided. The method dynamically compensates for dispersion in an optical signal by recovering a first clock and a second clock from a first polarization component and a second polarization component of the optical signal respectively, determining a delay time between the first clock and the second clock, determining the dispersion based on the delay time and dynamically compensating for the determined dispersion. The system comprises a polarization beam splitter, a clock recoverer, a dispersion determiner and a tunable dispersion compensation module and is operable to dynamically compensate for the dispersion in an optical signal.

Abstract: An optical protection switch and a method for optical protection switching are provided. The optical protection switch includes a loop mirror-based optical switch with two circulators and a direction-dependent phase shifter in the loop mirror. The direction-dependent phase shifter introduces phase shifts in counter-propagating optical signals in the loop mirror such that either one of a first optical signal and a second optical signal are switched as an output optical signal. The direction-dependent phase shifter is controlled by a controller which initiates switching from the first optical signal to the second optical signal if a drop in power level is detected in the first optical signal and a corresponding drop in power level is not detected in the second optical signal and vice versa.

Abstract: A system and method for in-service optical dispersion determination are provided. Optical dispersion is determined by splitting a first optical signal into two components, introducing a time delay between the two components such that corresponding pulses of the two components partially overlap, combining the two components to generate a combined optical signal comprising a first component and a second component, determining power of the combined optical signal while applying a plurality of dispersion compensation values, in order to determine a dispersion compensation value that results in a minimum detected power of the combined optical signal. Polarization Mode Dispersion is determined by adjusting the time delay that is introduced until the power of the combined optical signal is substantially equal for all of the plurality of dispersion compensation values.

Abstract: An optical component package is disclosed. The package has a housing. The interior of the housing is adapted to house an optical component. The package includes at least two fiber optic connectors, each comprising an component side adapted to connect to the optical component and each having a pluggable exterior element. Each of the at least two fiber optic connectors are mounted in the housing with their component side accessible from the interior of the package and their pluggable exterior element accessible from the exterior.

Abstract: An optical protection switch and a method for optical protection switching are provided. The optical protection switch includes a loop mirror-based optical switch with two circulators and a direction-dependent phase shifter in the loop mirror. The direction-dependent phase shifter introduces phase shifts in counter-propagating optical signals in the loop mirror such that either one of a first optical signal and a second optical signal are switched as an output optical signal. The direction-dependent phase shifter is controlled by a controller which initiates switching from the first optical signal to the second optical signal if a drop in power level is detected in the first optical signal and a corresponding drop in power level is not detected in the second optical signal and vice versa.

Abstract: A dynamic dispersion compensation system and method are provided. The method dynamically compensates for dispersion in an optical signal by recovering a first clock and a second clock from a first polarization component and a second polarization component of the optical signal respectively, determining a delay time between the first clock and the second clock, determining the dispersion based on the delay time and dynamically compensating for the determined dispersion. The system comprises a polarization beam splitter, a clock recoverer, a dispersion determiner and a tunable dispersion compensation module and is operable to dynamically compensate for the dispersion in an optical signal.

Abstract: A selective WDM add-channel system and method for adding channels to a WDM (wavelength division multiplexed) signal input to produce a WDM signal output while protecting against signal collisions are provided. The method protects against signal collisions by determining channel wavelengths of add-channel signals and at least one of the WDM signal input and the WDM signal output to ensure that channels that are added to the WDM signal input have different channel wavelength than each other and the channels that are already part of the WDM signal input. The selective WDM add-channel system comprises a selective combiner and a controller and is operable to selectively combine a plurality of add-channel inputs with a WDM input signal to produce a WDM output signal based on the channel wavelengths of the add-channel input signals and at least one of the WDM input signal and the WDM output signal.

Abstract: An optical component package is disclosed. The package has a housing. The interior of the housing is adapted to house an optical component. The package includes at least two fiber optic connectors, each comprising an component side adapted to connect to the optical component and each having a pluggable exterior element. Each of the at least two fiber optic connectors are mounted in the housing with their component side accessible from the interior of the package and their pluggable exterior element accessible from the exterior.

Abstract: A simple and flexible WDM laser source is disclosed using a loop erbium-doped fiber amplifier (LEDFA) configuration. The loop serves as a mirror and as an amplification medium. The laser cavity was made from the loop mirror and a set of fiber Bragg gratings (FBGs) which select the proper lasing wavelengths. The FBGs can be placed either in parallel or in series at the output of the loop configuration. Optical attenuators are placed in front of the FBG to control the flatness of the laser source output and determine the required lasing condition for each wavelength to avoid competition of the different lasing wavelengths. This configuration is flexible for adding any number of wavelengths as long as enough amplified spontaneous emission (ASE) is generated in the loop. Signal to noise ratio as high as 55-dB can be achieved.

Abstract: In order to reduce amplified spontaneous emission noise in the output signal of an amplifier of the kind in which amplification introduces amplified spontaneous emission, for example an erbium-doped fiber amplifier, the amplified signal is filtered using a loop mirror filter. The loop mirror filter may comprise a 3-dB fiber coupler with a loop of linear active fiber connected between two of its ports. The amplified signal and the filtered signal may be applied to, and extracted from, one of its other ports, conveniently by way of a circulator.

Abstract: In optical amplifiers of the kind in which a so-called loop mirror is formed by connecting the ends of a loop of active optical fiber to a 3 dB coupler, improved signal-to-noise ratios are obtained by coupling pump energy into the loop without passing through the 3 dB coupler. The input signal and amplified output signal may be conveyed to and from the coupler by way of isolators connected to input and output ports of the amplifier. Alternatively, they may be conveyed by way of a circulator. Automatic gain control may be provided by means of a fiber grating, or other such wavelength-selective device, which reflects part of the amplified signal having a selected wavelength back into the loop, to provide lasing. The amount of energy so reflected may be controlled by an attenuator.

Abstract: In order to reduce amplified spontaneous emission noise in the output signal of an amplifier of the kind in which amplification introduces amplified spontaneous emission, for example an erbium-doped fiber amplifier, the amplified signal is filtered using a loop mirror filter. The loop mirror filter may comprise a 3-dB fiber coupler with a loop of linear active fiber connected between two of its ports. The amplified signal and the filtered signal may be applied to, and extracted from, one of its other ports, conveniently by way of a circulator.

Abstract: In optical amplifiers of the kind in which a so-called loop mirror is formed by connecting the ends of a loop of active optical fiber to a 3 dB coupler, improved signal-to-noise ratios are obtained by coupling pump energy into the loop without passing through the 3 dB coupler. The input signal and amplified output signal may be conveyed to and from the coupler by way of isolators connected to input and output ports of the amplifier. Alternatively, they may be conveyed by way of a circulator. Automatic gain control may be provided by means of a fiber grating, or other such wavelength-selective device, which reflects part of the amplified signal having a selected wavelength back into the loop, to provide lasing. The amount of energy so reflected may be controlled by an attenuator.