Methods, systems, and apparatus, for an external cavity FP laser. In one aspect, an apparatus is provided that includes a FP laser diode; a Faraday rotator (FR) coupled to receive an optical output of the FP laser diode and that rotates a polarization of the optical output; an optical fiber coupled at a first end to receive the output of the FR; a WDM filter coupled to a second end of the optical fiber to receive the optical signal from the optical fiber; and a FRM coupled directly or indirectly to an output of the WDM filter, wherein an optical output of the WDM filter is partially reflected by the FRM such that the polarization of a reflected beam is rotated, and wherein the reflected optical signal then passes through the FR with its polarization being rotated by the FR before it is injected back into the FP laser diode.

An optical remodulator includes: a polarization diversity modulator configured to modulate an input optical signal to generate an output optical signal by using a first optical modulator implemented for a first polarization state and a second optical modulator implemented for a second polarization state that is orthogonal to the first polarization state; a photo detector configured to optical-to-electrical convert the input optical signal or the output optical signal or both of the optical signals into an electric signal; and a drive signal generator configured to generate a first drive signal that drives the first optical modulator and a second drive signal that drives the second optical modulator based on the electric signal generated by the photo detector.

A method and system for distributed spatial mode processing is disclosed a number of optical signals are received over an optical link. Each optical signal is received via a respective one of a number of spatial modes of the optical link. The optical link includes a particular spatial mode not used for the receiving. A first one of the number of optical signals received from a first one of the number of spatial modes is transferred to a second one of the number of spatial modes via the particular spatial mode, wherein the first one of the number of optical signals is transmitted via the second one of the number of spatial modes.

An optical access network comprises an optical network unit having a first port for connecting to a first optical link, a second port for connecting to a second optical link and an optical source. The optical source is arranged to generate a first optical signal, to transmit the first optical signal via the first port, to receive an optical seed signal via the first port and to amplify the optical seed signal. The optical seed signal has a narrower bandwidth compared to the first optical signal. A modulator is arranged to modulate the amplified optical seed signal with upstream data to form an upstream optical signal and to transmit the upstream optical signal via the second port. A polarisation modifier can modify polarisation of the first optical signal.

In an example embodiment, a WDM array includes an optical filter, N common ports, N reflection ports, and N pass ports. The N common ports may be positioned to a first side of the optical filter. N may be greater than or equal to two. The N reflection ports may be positioned to the first side of the optical filter. The N pass ports may be positioned to a second side of the optical filter opposite the first side.

The concepts and technologies disclosed herein are directed to alarm correlation and ticketing for reconfigurable optical add/drop multiplexer (ROADM) networks. According to one aspect disclosed herein, a ROADM controller can create, based upon data associated with a plurality of ROADM network elements operating in a ROADM network, a graph of the plurality ROADM network elements. The ROADM controller can retrieve a plurality of alarms from at least a portion the plurality of ROADM network elements, associate the plurality of alarms with at least the portion of the plurality of ROADM network elements, and associate a direction of each alarm with a corresponding service direction. The ROADM controller can eliminate any alarms with a time stamp outside of a same time window. The ROADM controller can then determine that any remaining alarms are associated with a root cause of a failure within the ROADM network.

Data center interconnections, which encompass WSCs as well as traditional data centers, have become both a bottleneck and a cost/power issue for cloud computing providers, cloud service providers and the users of the cloud generally. Fiber optic technologies already play critical roles in data center operations and will increasingly in the future. The goal is to move data as fast as possible with the lowest latency with the lowest cost and the smallest space consumption on the server blade and throughout the network. Accordingly, it would be beneficial for new fiber optic interconnection architectures to address the traditional hierarchal time-division multiplexed (TDM) routing and interconnection and provide reduced latency, increased flexibility, lower cost, lower power consumption, and provide interconnections exploiting NMD Gbps photonic interconnects wherein N channels are provided each carrying M wavelength division signals at D Gbps.

System and method for managing spectral hole burning (SHB) effect in an optical transport network (OTN) link. The method is performed by an automatic gain control (AGC) circuit of an amplification assembly of the OTN link. The method comprises determining, via a first photodetector communicatively connected to the AGC circuit, an input power of an income signal and, in response to the input power being less than a predetermined portion of a full-loading signal power, causing a pump power variable attenuator (PVOA) of the amplification assembly to attenuate pump power from a pump source, the PVOA being disposed optically intermediate a first doped fiber and a second doped fiber of the amplification assembly.

Provided is an optical communication device including: a multiplexer configured to multiplex one or more input optical signals to output a single first optical signal; a signal generator configured to generate a second optical signal having a preset wavelength; a filter configured to generate a third optical signal by combining the first optical signal and the second optical signal; a switch configured to connect any one of a plurality of optical cables connected to the switch with the filter to transmit the third optical signal through any one of the plurality of optical cables; and a controller configured to control the switch by analyzing reflected light of the second optical signal.

An optical communication device includes: a first optical switch that is connected to a plurality of optical transmission lines and outputs an optical signal input from any of the optical transmission lines to another optical transmission line; a second optical switch that is connected to a plurality of optical transmission lines and outputs an optical signal input from any of the optical transmission lines to another optical transmission line; and a multicast transfer unit configured to perform multicast transfer of an optical signal transmitted from a first device connected to the first optical switch to one or more second devices connected to the second optical switch.