Abstract: Techniques for improving gain equalization in C- and L-band (“C+L”) erbium-doped fiber amplifier (EDFAs) are provided. For example, the C- and L-band amplification sections of a C+L EDFA may be separated and configured in a parallel arrangement or a serial arrangement. For both the parallel and serial arrangements, the C- and L-band amplification sections may share a common gain flattening filter (GFF) or each amplification section may include and employ a separate GFF. Moreover, in some examples, an “interstage” L-band GFF may be located before or upstream of the L-band amplification section such that the L-band optical signal is gain-equalized or flattened prior to the L-band amplification section amplifying the L-band.

Abstract: Disclosed are techniques and amplifier stages that include wave division multiplexers, semiconductor optical amplifiers and wave division demultiplexers that amplify optical signals. An input optical signal having a first bandwidth is partitioned into a plurality of subband optical signals by thin film filters tuned to a selected bandwidth that is less than the first bandwidth. Each of the plurality of subband optical signals has a bandwidth that is a portion of the first bandwidth. Each subband optical signal is input into a semiconductor optical amplifier that is tuned to the respective portion of the first bandwidth that corresponds to the subband optical signal. The combination of the partitioned input optical signal and tuned semiconductor optical amplifiers provides improved optical signal transmission performance by reducing polarization dependent gain.

Abstract: Disclosed are techniques and amplifier stages that include wave division multiplexers, semiconductor optical amplifiers and wave division demultiplexers that amplify optical signals. An input optical signal having a first bandwidth is partitioned into a plurality of subband optical signals by thin film filters tuned to a selected bandwidth that is less than the first bandwidth. Each of the plurality of subband optical signals has a bandwidth that is a portion of the first bandwidth. Each subband optical signal is input into a semiconductor optical amplifier that is tuned to the respective portion of the first bandwidth that corresponds to the subband optical signal. The combination of the partitioned input optical signal and tuned semiconductor optical amplifiers provides improved optical signal transmission performance by reducing polarization dependent gain.

Abstract: Techniques for managing gain equalization error in optical communication systems are provided. For example, a multi-stage gain correction filter may be configured to at least correct gain equalization error produced by filters with insufficient resolution, for example, conventional non-reflective gain correction technology used in the optical communication systems. The multi-stage filter may include at least a broadband gain correction filter to correct gain equalization error in most of the transmission bandwidth and a narrow band gain correction filter to correction error in a narrow region of the bandwidth. One or more of the multi-stage filters may be implemented in the repeaters of the system (which may be referred to as hybrid GFFs) or may be included in a standalone body (which may be referred to as hybrid GEFs).

Abstract: Disclosed are techniques and amplifier stages that include wave division multiplexers, semiconductor optical amplifiers and wave division demultiplexers that amplify optical signals. An input optical signal having a first bandwidth is partitioned into a plurality of subband optical signals by thin film filters tuned to a selected bandwidth that is less than the first bandwidth. Each of the plurality of subband optical signals has a bandwidth that is a portion of the first bandwidth. Each subband optical signal is input into a semiconductor optical amplifier that is tuned to the respective portion of the first bandwidth that corresponds to the subband optical signal. The combination of the partitioned input optical signal and tuned semiconductor optical amplifiers provides improved optical signal transmission performance by reducing polarization dependent gain.

Abstract: Apparatus, systems, and techniques for extending distributed acoustic sensing (DAS) range in undersea optical cables over multiple spans, as well as providing span-specific DAS information, are provided.

Abstract: Techniques for managing gain equalization error in optical communication systems are provided. For example, a multi-stage gain correction filter may be configured to at least correct gain equalization error produced by filters with insufficient resolution, for example, conventional non-reflective gain correction technology used in the optical communication systems. The multi-stage filter may include at least a broadband gain correction filter to correct gain equalization error in most of the transmission bandwidth and a narrow band gain correction filter to correction error in a narrow region of the bandwidth. One or more of the multi-stage filters may be implemented in the repeaters of the system (which may be referred to as hybrid GFFs) or may be included in a standalone body (which may be referred to as hybrid GEFs).

Abstract: Techniques for improving redundancy in semiconductor-based optical communication systems are provided. For example, two or more semiconductor optical amplifiers (SOAs) may be provided in an optical repeater, and each SOA may form a respective amplification path. When failure occurs on a first SOA, a second SOA that is different from the first SOA can be selected. In one example, the selection may be based on wavelength division multiplexing (WDM), and in another example, the selection may be based on optical switching. The two or more SOAs (and other optical components) may be integrated in the same substrate package.

Abstract: Techniques for improving redundancy in semiconductor-based optical communication systems are provided. For example, two or more semiconductor optical amplifiers (SOAs) may be provided in an optical repeater, and each SOA may form a respective amplification path. When failure occurs on a first SOA, a second SOA that is different from the first SOA can be selected. In one example, the selection may be based on wavelength division multiplexing (WDM), and in another example, the selection may be based on optical switching. The two or more SOAs (and other optical components) may be integrated in the same substrate package.