Optical fiber network with improved fiber utilization

A passive optical fiber network system for bidirectional transmission of downstream and upstream digital data traffic between a plurality of data sources and a plurality of end user devices, the data traffic comprising data to be transmitted specifically to and from one of said data sources and one of said end user devices, the system comprising:

• a plurality of OLTs in communication with said data sources and designatable by sequential numbers 1 to “N”, each OLT having an OLT optical connection;
• a plurality of ONUs, each said ONU having an ONU optical connection and being appointed to be in communication with a predetermined one of said OLTs said ONUs being equal in number to said OLTs forming an ordered pairs and each said user device being appointed to be in communication with a predetermined one of said ONUs;
• a media access control system present in each of the OLTs having a burst mode clock recovery circuit to recover the timing needed for each of data transmission and configured to identify and maintain the integrity of both the upstream and downstream data associated with each OLT, ONU, and end user device;
• N OLT-side wavelength converters, each said converter being associated with a particular one of said OLTs and having an OLT port and a multiplexer port;
• N ONU-side wavelength converters, each said converter being associated with a particular one of said OLT-side wavelength converters and having an ONU port and a demultiplexer port;
• an OLT-side optical multiplexer having at least N branching ports and one common port;
• said bidirectional communication between OLT multiplexer port and ONU port being effected through a single optical fiber as a high Gbps rate upstream burst mode signal with a first bit valid verification to ascertain the integrity of a burst-mode data stream as well as a high Gbps continuous mode downstream signal corresponding to each of N OLT side devices and each of N ONU side devices;
• said single optical fiber additionally carrying a low Gbps rate continuous mode monitoring the integrity of the optical fiber;
• an ONU-side optical demultiplexer having at least N branching ports and one common port;
• a multiplex optical fiber communicatively connecting said common port of said OLT-side optical multiplexer and said common port of ONU-side optical demultiplexer;
• and wherein, for all values of “i” ranging from 1 to N:
• a unique intermediate downstream wavelength λiD and a unique intermediate upstream wavelength λiU are assigned to the “i-th” of said OLT-side wavelength converters and the “i-th” of said ONU-side wavelength converters;
• the “i-th” said OLT is connected for data communications via its OLT optical connection to the OLT port of the “i-th” said OLT-side wavelength converter and is configured:
• i. to be communicatively coupled to one of said data sources, from which downstream data for said end user devices is to be received and to which upstream data from said end user devices is to be transmitted;
• ii. to transmit said downstream data to the ONU predetermined for said OLT;
• iii. to receive said upstream stream data from said predetermined ONU;
• and
• said OLT transmitting said downstream data at a downstream base wavelength “λBD and receiving said upstream data at an upstream base wavelength “λBU” through an OLT optical connection;
• and
• i. said multiplexer port of said “i-th” OLT-side wavelength converter is communicatively coupled to the “i-th” said branching port of said OLT-side optical multiplexer;
• each of said ONUs is connected for data communications via its ONU optical connection to the ONU port of the ONU-side wavelength converter with which said ONU is associated and each said ONU is configured:
• i. to be communicatively coupled to at least one of the end user devices, to which said downstream data is to be transmitted and from which said upstream data is to be received;
• ii. to receive said downstream data from the OLT in communication with said ONU;
• iii. to transmit said upstream stream data to said OLT;
• and
• iv. said ONU receiving said downstream data at said downstream base wavelength λBD and transmitting said upstream data at said upstream base wavelength λBU through an ONU optical connection;
• said demultiplexer port of the “i-th” said ONU-side wavelength converter is communicatively coupled to the “i-th” said branching port of said ONU-side optical demultiplexer;
• the “i-th” said OLT-side wavelength converter is operable to convert light at wavelength λBD that is input at its OLT port to light at a wavelength λiD carrying said downstream data that is output at its multiplexer port, and to convert light at wavelength λBU carrying said upstream data that is input at its multiplexer port to light at wavelength λiU that is output at its OLT port;
• the “i-th” said ONU-side wavelength converters is operable to convert light at wavelength λiD that is input at its demultiplexer port to light at wavelength λBD carrying said downstream data that is output at its ONU port, and to convert light at wavelength λBU carrying said upstream data that is input at its ONU port to light at wavelength λiU that is output at its multiplexer port;
• said OLT-side optical multiplexer is operable to:
• i. receive through its “i-th” branching port downstream data at said intermediate downstream wavelength λiD, and aggregate and output all said downstream data as a multiplexed downstream data signal through its common port to said multiplex optical fiber;
• and
• ii. receive from said multiplex optical fiber through its common port an upstream multiplexed data signal including light of any one or more of said intermediate upstream wavelengths and demultiplex said signal by sending substantially all of the light of wavelength λiU to said i-th branching port of said multiplexer;
• said ONU-side optical demultiplexer is operable to:
• i. receive through its “i-th” branching port upstream data at said intermediate upstream wavelength λiU, and aggregate and output all said upstream data as said upstream multiplexed upstream data signal through its common port to said multiplex optical fiber;
• and
• ii. receive from said multiplex optical fiber through its common port said multiplexed downstream data signal including light of any or all of said intermediate downstream wavelengths and demultiplex said signal by sending substantially all of the light of wavelength λiD to the i-th branching port of said multiplexer.

A kit of parts for retrofitting an optical fiber network system configured for bidirectional transmission of downstream and upstream digital data traffic between a plurality of data sources and a plurality of end user devices, the data traffic comprising data to be transmitted specifically to and from one or more of said end user devices, the kit including:

• a plurality of “N” OLT-side wavelength converters;
• a plurality of N ONU-side wavelength converters;
• an OLT-side optical multiplexer having at least N branching ports and one common port;
• and
• an ONU-side optical demultiplexer having at least N branching ports and one common port;
• and wherein, for all 1″ values ranging sequentially from 1 to N:
• said bidirectional communication between OLT multiplexer port and ONU port being effected through a single optical fiber as a high Gbps rate upstream burst mode signal with a first bit valid verification to ascertain the integrity of a burst-mode data stream as well as a high Gbps continuous mode downstream signal corresponding to each of N OLT side devices and each of N ONU side devices;
• said single optical fiber additionally carrying a low Gbps rate continuous mode monitoring the integrity of the optical fiber;
• the “i-th” said OLT wavelength converter is operable:
• i. to convert light at wavelength λBD that is appointed to carry downstream data and input at its OLT port to light at a unique preselected downstream wavelength λiD that is output at its multiplexer port;
• and
• ii. to convert light at wavelength λBU that is appointed to carry upstream data that is input at its multiplexer port to light at a unique, preselected upstream wavelength λiU that is output at its OLT port;
• the “i-th” said ONU-side wavelength converter is operable:
• i. to convert light at wavelength λiD appointed to carry said downstream data that is input at its demultiplexer port to light at wavelength λBD that is output at its ONU port;
• and
• ii. to convert light at wavelength λBU carrying said upstream data that is input at its ONU port to light at wavelength λiU that is output at its multiplexer port;
• the “i-th” said branching port of said OLT-side optical multiplexer is adapted to be connected to the multiplexer port of the “i-th” said OLT-side wavelength converter;
• said OLT-side optical multiplexer is operable to:
• i. receive through its “i-th” said branching port downstream data at said intermediate downstream wavelength λiD, and aggregate and output all said downstream data as a multiplexed downstream data signal through its common port to said multiplex optical fiber;
• and
• ii. receive from said multiplex optical fiber through its common port an upstream multiplexed data signal including light of any one or more of said intermediate upstream wavelengths and demultiplex said signal by sending substantially all of the light of wavelength λiU to the i-th said branching port of said multiplexer;
• the “i-th” said branching port of said ONU-side optical demultiplexer is adapted to be connected to the demultiplexer port of the “i-th” said ONU-side wavelength converter;
• said common port of said ONU-side optical demultiplexer is adapted to be connected to said common port of said OLT-side optical multiplexer;
• wherein said ONU-side optical demultiplexer is operable to:
• i. receive through its “i-th” branching port upstream data at intermediate upstream wavelength λiU, and aggregate and output all said upstream data as said upstream multiplexed upstream data signal through its common port to said multiplex optical fiber;
• and
• ii. receive from said multiplex optical fiber through its common port said multiplexed downstream data signal including light of any or all of said intermediate downstream wavelengths λiD, and demultiplex said signal by sending substantially all of the light of wavelength λiD to said i-th branching port of said multiplexer.

In a method for bidirectional optical transmission of downstream and upstream digital data traffic between a plurality of “N” OLTs designatable by sequential numbers from 1 to “N” and communicatively connected to a plurality of data sources and an equal plurality of “N” ONU groups, each associated with a specific one of the OLTs and comprising at least one ONU, each ONU being communicatively connected to an end user device, the data traffic comprising downstream data sets, each appointed to be transmitted from one of said data sources to a specific one of said end user devices and upstream data sets, each appointed to be transmitted from one of said end user devices to a specific one of said data sources, and wherein each said downstream data set is optically transmitted from one of said OLTs and received by the ONU associated therewith as downstream light having a downstream base wavelength λBD and each said upstream data set is optically transmitted from one of said ONUs and received by the OLT associated therewith as upstream light having an upstream base wavelength λBU,

• the improvement wherein the method further comprises, for all values of “i” ranging from 1 to N:
• converting said light at wavelength λBD transmitted by said “i-th” OLT to converted downstream light having a unique intermediate downstream wavelength λiD;
• multiplexing said converted downstream light into multiplexed downstream light comprising a plurality of downstream spectral components, each encompassing one of said intermediate downstream wavelengths λiD;
• transmitting said multiplexed downstream light through a multiplex optical fiber as burst mode signals;
• demultiplexing said multiplexed downstream light transmitted through said multiplex optical fiber to separate said downstream spectral components;
• reconverting light of each of said downstream spectral components back into reconverted light at said downstream base wavelength λBD;
• receiving light reconverted from the downstream spectral component encompassing wavelength λiD at said “i-th” ONU;
• converting said light at wavelength λBU transmitted by said “i-th” ONU to converted upstream light having a unique intermediate upstream wavelength λiU;
• multiplexing said converted upstream light into multiplexed upstream light comprising a plurality of upstream spectral components, each encompassing one of said intermediate upstream wavelengths λiU;
• transmitting said multiplexed upstream light through said multiplex optical fiber as burst mode signals at a high Gbps rate;
• demultiplexing said multiplexed upstream light transmitted through said multiplex optical fiber to separate said upstream spectral components;
• reconverting light of each of said upstream spectral components back into reconverted light at said upstream base wavelength λBU;
• receiving light reconverted from the upstream spectral component encompassing wavelength λiU at said “i-th” OLT.