US-12621076-B2 - Add/drop capability for spatial division multiplexed optical systems

US12621076B2US 12621076 B2US12621076 B2US 12621076B2US-12621076-B2

Abstract

Various example embodiments for supporting optical transport systems are presented. Various example embodiments for supporting optical transport systems may be configured to support optical transport systems that support multiple fibers based on use of spatial division multiplexing (SDM) techniques. Various example embodiments for supporting optical transport systems that support multiple fibers based on use of SDM techniques may be configured to support optical transport systems that support multiple fibers based on use of an anylane add/drop capability that is based on use of a Clos architecture (e.g., a spatially-switched distributed Clos architecture with a single stage of switching for network traffic that passes through the node, a spatially-switched distributed Clos architecture with two stages of switching for network traffic that passes through the node, a spatially-switched node-contained Clos architecture with three stages of switching for network traffic that passes through the node, or the like).

Inventors

JOHN SIMSARIAN
David Neilson
Roland Ryf

Assignees

NOKIA SOLUTIONS AND NETWORKS OY

Dates

Publication Date: 20260505
Application Date: 20221013

Claims (12)

1 . An apparatus, comprising: an optical add-drop multiplexer configured to optically switch optical communications between near ends of optical fibers or optical cores such that, for selected pairs of the optical fibers, an entire set of optical wavelength channels received at the optical add-drop multiplexer from a first of the optical fibers or a first of the optical cores thereof of each one of the selected pairs of the optical fibers is directed together to a second of the optical fibers or a second of the optical cores thereof of the same one of the selected pairs of the optical fibers, wherein the optical add-drop multiplexer comprises: a transport section comprising a first plurality of optical switches configured to optically switch optical communications between near ends of optical fibers or optical cores thereof such that entire sets of optical wavelength channels received from ones of the optical fibers or the optical cores thereof are directed together to others of the optical fibers or the optical cores thereof; and an add-drop section comprising a second plurality of optical switches configured to drop entire sets of optical wavelength channels from selected ones of the optical fibers or the optical cores thereof and to add entire sets of optical wavelength channels to selected others of the optical fibers or the optical cores thereof, wherein each of the optical switches in the second plurality of optical switches is optically connected to each of the optical switches in the first plurality of optical switches such that any of the sets of optical wavelength channels being dropped is dropped together from one of the optical fibers or the optical cores thereof and such that any of the sets of optical wavelength channels being added is added together to one of the optical fibers or the optical cores thereof.
2 . The apparatus of claim 1 , wherein the optical add-drop multiplexer is configured to selectively drop an entire set of optical wavelength channels received from selected ones of the optical fibers or the optical cores thereof and to add sets of optical wavelength channels to selected others of the optical fibers or the optical cores thereof such that the added sets are the wavelength channels carried by the selected others.
3 . The apparatus of claim 1 , wherein the optical add-drop multiplexer comprises a multi-stage structure of optical switches therein.
4 . The apparatus of claim 3 , wherein the multi-stage structure includes a Clos network of optical switches.
5 . The apparatus of claim 3 , wherein the multi-stage structure includes, at least, a first ingress and/or egress layer of optical switches, a second ingress and/or egress layer of optical switches, and a first intermediate layer of optical switches connecting the first and second ingress and/or egress layers of optical switches.
6 . The apparatus of claim 5 , wherein the multi-stage structure includes a second intermediate layer of optical switches connecting the first intermediate layer of optical switches to the second ingress and/or egress layer of optical switches.
7 . The apparatus of claim 1 , further comprising: the optical fibers; and a plurality of optical transceivers, each optical transceiver being connected to receive and transmit optical signals to a remote end of a corresponding pair of the optical fibers or a corresponding pair of the optical cores over a plurality of optical wavelength channels.
8 . An apparatus, comprising: an optical add-drop multiplexer configured to optically switch optical communications between near ends of optical fibers or optical cores such that, for selected pairs of the optical fibers, an entire set of optical wavelength channels received at the optical add-drop multiplexer from a first of the optical fibers or a first of the optical cores thereof of each one of the selected pairs of the optical fibers is directed together to a second of the optical fibers or a second of the optical cores thereof of the same one of the selected pairs of the optical fibers, wherein the optical add-drop multiplexer comprises: a transport section comprising a first plurality of optical switches and a second plurality of optical switches, wherein the first plurality of optical switches is optically connected to near ends of input optical fibers or optical cores thereof and optically connected to the second plurality of optical switches, wherein the second plurality of optical switches is configured to optically switch optical communications between the first plurality of optical switches and near ends of optical output fibers or optical cores thereof, wherein the first plurality of optical switches and the second plurality of optical switches are configured to optically switch optical communications between near ends of optical fibers or optical cores thereof such that entire sets of optical wavelength channels received from ones of the input optical fibers or the optical cores thereof are directed together to ones of the output optical fibers or the optical cores thereof; and an add-drop section comprising a third plurality of optical switches configured to drop entire sets of optical wavelength channels from selected ones of the input optical fibers or the optical cores thereof and to add entire sets of optical wavelength channels to selected ones of the output optical fibers or the optical cores thereof, wherein each of the optical switches in the third plurality of optical switches is optically connected to each of the optical switches in the second plurality of optical switches such that any of the sets of optical wavelength channels being dropped is dropped together from one of the input optical fibers or the optical cores thereof and such that any of the sets of optical wavelength channels being added is added together to one of the output optical fibers or the optical cores thereof.
9 . An apparatus, comprising: an optical add-drop multiplexer configured to optically switch optical communications between near ends of optical fibers or optical cores such that, for selected pairs of the optical fibers, an entire set of optical wavelength channels received at the optical add-drop multiplexer from a first of the optical fibers or a first of the optical cores thereof of each one of the selected pairs of the optical fibers is directed together to a second of the optical fibers or a second of the optical cores thereof of the same one of the selected pairs of the optical fibers, wherein the optical add-drop multiplexer comprises: a transport section comprising a first plurality of optical switches, a second plurality of optical switches, and a third plurality of optical switches; wherein the first plurality of optical switches is optically connected to near ends of input optical fibers or optical cores thereof and optically connected to the second plurality of optical switches, wherein the third plurality of optical switches is optically connected to the second plurality of optical switches and near ends of output optical fibers or optical cores thereof, wherein the second plurality of optical switches is optically connected to the first plurality of optical switches and the third plurality of optical switches; wherein the first, second, and third pluralities of optical switches are configured to optically switch optical communications between near ends of optical fibers or optical cores thereof such that entire sets of optical wavelength channels received from ones of the input optical fibers or the optical cores thereof are directed together to ones of the output optical fibers or the optical cores thereof; and wherein the first, second, and third pluralities of optical switches are configured to drop entire sets of optical wavelength channels from selected ones of the input optical fibers or the optical cores thereof and to add entire sets of optical wavelength channels to selected ones of the output optical fibers or the optical cores thereof.
10 . The apparatus of claim 9 , wherein the third plurality of optical switches is configured to drop entire sets of optical wavelength channels from selected ones of the input optical fibers or the optical cores thereof to corresponding drop fibers or optical cores thereof supported by each of the optical switches in the third plurality of optical switches.
11 . The apparatus of claim 9 , wherein the first plurality of optical switches is configured to add entire sets of optical wavelength channels to selected ones of the output optical fibers or the optical cores thereof from corresponding add fibers or optical cores thereof supported by each of the optical switches in the first plurality of optical switches.
12 . The apparatus of claim 9 , wherein the third plurality of optical switches is configured to drop entire sets of optical wavelength channels from selected ones of the input optical fibers or the optical cores thereof to corresponding drop fibers or optical cores thereof supported by each of the optical switches in the third plurality of optical switches, wherein the first plurality of optical switches is configured to add entire sets of optical wavelength channels to selected ones of the output optical fibers or the optical cores thereof from corresponding add fibers or optical cores thereof supported by each of the optical switches in the first plurality of optical switches.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/357,068, filed on Jun. 30, 2022, which is hereby incorporated herein by reference in its entirety. TECHNICAL FIELD Various example embodiments relate generally to optical systems and, more particularly but not exclusively, to spatial division multiplexed optical systems. BACKGROUND In optical systems, wavelength division multiplexing (WDM) may be employed to multiplex multiple optical carrier signals onto a single optical fiber using different wavelengths. In an WDM-based optical system, reconfigurable optical add/drop multiplexers (ROADMs) may be used to switch traffic from the WDM-based optical system at the wavelength level, thereby allowing individual wavelengths or multiple wavelengths to be added to and/or dropped from transport fibers without having to convert the signals to electronic signals and back to optical signals. Many ROADM-based WDM optical systems add and drop wavelengths using a colorless, directionless, contentionless, and flexible (CDCF) add/drop section architecture such that an optical signal plugged into any port of the CDCF add/drop section can have any wavelength (i.e., colorless) and can go in any direction (i.e., directionless), without wavelength contention (i.e., contentionless). In optical systems, the Shannon capacity limit of certain bands (e.g., the “conventional wavelength” communication band (C band) and the “long wavelength” communication band (L band)) is being approached. In order to support future capacity growth as the Shannon capacity limit of such bands is approached, many optical networks will be scaling in the spatial domain based on use of multiple fibers and/or multiple cores per fiber. This scaling in the spatial domain based on use of multiple fibers and/or multiple cores per fiber will provide multiple parallel paths between nodes. This provides a new dimension to optical transport networks that needs to be properly designed, configured, controlled, and managed in order to support increased capacity in optical systems. SUMMARY In at least some example embodiments, an apparatus includes an optical add-drop multiplexer configured to optically switch optical communications between near ends of optical fibers or optical cores such that, for selected pairs of the optical fibers, an entire set of optical wavelength channels received at the optical add-drop multiplexer from a first of the optical fibers or the optical cores thereof of each one of the selected pairs of the optical fibers is directed together to a second of the optical fibers or the optical cores thereof of the same one of the selected pairs of the optical fibers. In at least some example embodiments, the optical add-drop multiplexer is configured to selectively drop an entire set of optical wavelength channels received from selected ones of the optical fibers or the optical cores thereof and to add sets of optical wavelength channels to selected others of the optical fibers or the optical cores thereof such that the added sets are the wavelength channels carried by the selected others. In at least some example embodiments, the optical add-drop multiplexer includes a multi-stage structure of optical switches therein. In at least some example embodiments, the multi-stage structure includes a Clos network of optical switches. In at least some example embodiments, the multi-stage structure includes, at least, a first ingress and/or egress layer of optical switches, a second ingress and/or egress layer of optical switches, and a first intermediate layer of optical switches connecting the first and second ingress and/or egress layers of optical switches. In at least some example embodiments, the multi-stage structure includes a second intermediate layer of optical switches connecting the first intermediate layer of optical switches to the second ingress and/or egress layer of optical switches. In at least some example embodiments, the apparatus further includes the optical fibers and a plurality of optical transceivers, each optical transceiver being connected to receive and transmit optical signals to a remote end of a corresponding pair of the optical fibers or a corresponding pair of the optical cores over a plurality of optical wavelength channels. In at least some example embodiments, a method of directing wavelength division multiplexed sets of optical signals between nearby ends of optical fibers at an optical add-drop multiplexer includes, for a plurality of pairs of optical fibers, optically directing optical communications between near ends of the optical fibers such that an entire set of optical wavelength channels received at the optical add-drop multiplexer from a first of the optical fibers or the optical cores thereof of a first optical fiber of one of the selected pairs of the optical fibers is directed together to a second of the optical fibers or the optical core