Xtera Communications, Inc.

Neptune Subsea IP Limited

Do-Il Chang

Wayne S Pelouch

Herve A Fevrier

Stephen Michael Webb

John G Ellison

Philippe Andre Perrier

Andrej B Puc

Wayne S Peloch

A submarine optical repeater includes a submarine amplifier module, which further includes a pumping laser module and an optical detector module. The pumping laser module generates optical amplifications within an optical cable, and, in the case of a fault in the optical cable, the optical detector module detects at least one characteristic of an optical signal caused by the fault in the optical cable. This configuration then identifies a particular signal characteristic that indicates a fault within the optical cable.

Repeater OTDR using repeater based Raman pumps

An apparatus includes a remote optically pumped amplifier (ROPA). The ROPA includes a bypass filter configured to receive an optical signal and first pump power and to separate the optical signal and the first pump power. The ROPA also includes an amplifier configured to receive the optical signal from the bypass filter and to amplify the optical signal. The ROPA further includes an optical combiner/multiplexer configured to receive the first pump power from the bypass filter, receive at least second and third pump powers, combine at least two of the first, second and third pump powers, and provide different pump powers or combinations of pump powers to different locations within the ROPA to feed the amplifier.

Optical transmission system and related remote optically pumped amplifier (ROPA) and method

Repeater OTDR using repeater based raman pumps

A remote optically pumped amplifier in a multi-span optical communications link. A backwards Raman pump module performs backwards Raman amplification in an optical communications span that contains the remote optically pumped amplifier. A residual amount of backwards Raman pump power is then used to power the remote optically pumped amplifier. The remote optically pumped amplifier may be located 40 to 120 kilometers in optical distance from the backwards Raman pump module such that at least three milliwatts of residual Raman pump power is received by the remote optically pumped amplifier. The Raman pump module may be a multi-pump Raman pump module. A controller controls pump power provided by at least one of the pumps of the backwards Raman pump module, so as to at least partially compensate for optical signal strength versus wavelength variation introduced by the remote optically pumped amplifier and the backwards Raman pump module.

Multi-span optical communications link having remote optically pumped amplifier

The adjustment of tilt in an optical signal path of a repeater. The repeater includes an optical pump that optically powers a rare-Earth doped fiber amplifier, which amplifies the optical signal. The optical signal path also includes Raman gain stage implemented in a previous optical fiber span in the optical signal path, and which contributes tilt with respect to wavelength. Adjusting the Raman gain and/or the rare-Earth doped gain also adjusts the combined tilt contributed by these gain stages. However, the rare-Earth doped gain operates at least partially in the saturated regime, thereby stabilizing the gain at the output of the rare-Earth doped amplifier. Thus tilt control may be employed by adjusting optical pump power with reduced effect on overall gain.

Tilt control through optical pump power adjustment

An optical assembly in an optical link coupling two optical terminals. The optical assembly receives and demultiplexes two groups of optical wavelength channels which are each treated separately as far as dispersion compensation and discrete amplification are concerned. The optical assembly then multiplexes the two groups back into the same fiber for further transmission. For instance, one group of optical wavelength channels may each be coherent channels, and subject to no dispersion in the optical assembly, while the other group may contain non-coherent channels, which are subject to dispersion compensation in the optical assembly.

Distinct dispersion compensation for coherent channels

The mixing of coherent optical wavelength channels with non-coherent optical wavelength channels. Before mixing, a dispersive element introduces dispersion into the coherent optical wavelength channels and/or into the non-coherent optical wavelength channels such that the dispersion map of the coherent optical wavelength channels is different than the dispersion map of the non-coherent optical wavelength channels. By allowing the coherent channels to have a different dispersion map, the dispersion map may be moved further from the zero dispersion point, which can degrade coherent detection. Accordingly, coherent optical channels and non-coherent optical channels may be transmitted effectively over the same optical link.

Introduction-side dispersion shifting of channels

The alteration of the bandwidth of an optical amplifier. Before alteration, optical signals having a first set of wavelengths are provided through a gain medium of the optical amplifier. In addition, a first pump having a set of pump wavelengths is propagated through the gain medium to thereby amplify the optical signals. After alteration, optical signals having at least a partially different set of wavelengths are able to be optically amplified by coupling a second pump into the optical medium. The second pump is at least partially distinct from the first pump in that the second pump includes at least one pump wavelength that was not included in the first pump.

Optical amplifier bandwidth alteration

An optical amplification mechanism that introduces optical pump(s) into one port of an optical circulator. The optical circulator directs the optical pumps from that port into another port that is coupled to the output of a gain stage. The optical pump(s) then pass from the output to the input of the gain stage while amplifying an optical signal passing from the input to the output of the gain stage. A residual amount of optical pump(s) that exits the input of the gain stage is reflected back into the input of the gain stage. The reflected optical pump(s) then further assists in the amplification of the optical signal. Other embodiments are also disclosed.

Optical amplifier with Raman and rare-earth-doped fiber amplifier both pumped efficiently using direct and reflected pump light

Optical amplification by combining two or more optical signals from separate optical fibers, amplifying the combined signal using an optical fiber, and separating the amplified signals into their constituent optical signals. The separated optical signals may then be sent further in the direction they had been heading before combination. This allows multiple optical signals to be amplified using a single optical amplifier, perhaps even in a single optical fiber. Although not required, the two optical signals may even be travelling in different directions.

Optical amplifier capable of amplifying optical signals that traverse separate transmission fibers

Cross-distribution of the output pump power from optical pump units amongst multiple amplifier gain stages even in a single direction of an optical link in an optical communications system. For example, an optical pump unit may output optical pump power that is shared amongst a discrete optical amplification unit and a distributed optical amplification unit (such as a forward and/or backward Raman amplifier). Such sharing has the potential to increase reliability and/or efficiency of the optical communications system.

Optical communication using shared optical pumps

A submarine optical repeater that shares optical pump power in multiple gain stages such that approximately the same wavelengths of optical pump is provided to each of the gain stages. Also, tilt control mechanism may adjust gain dependency on wavelength by adjusting the amount of optical pump power delivered to the optical gain stages. Residual optical pump power from both forward and backward Raman amplification may be used to power corresponding optically pumped amplifiers.

Submarine optical repeater

Embodiments described herein relate to an optical fiber stretch that may experience forward Raman amplification in which the peak optical signal power occurs at some distance from the transmitter. Smaller effective area optical fiber is used at a portion of the optical fiber stretch in which the optical signal power is increasing, while larger effective area optical fiber is used at a more remote stretch of the optical fiber stretch that experiences the peak optical signal power. Thus, the quality of the signal is better preserved since the larger effective area fiber reduces maximum optical signal density thereby reducing non-linear degradations on signal quality.

Growing community of inventors

Allen, TX, United States of America

Do-Il Chang