Optical interconnection arrangement for high speed, high density communication systems
View Patent ↗An optical interconnection arrangement for use in high data applications is presented that eliminates the need for extensive serialization/de-serialization (SERDES) functionality by utilizing pulse amplitude modulation (PAM) techniques to represent the data in the optical domain while utilizing a separate channel for transmitting an optical clock signal, eliminating the need for clock recovery circuitry on the receive end of the arrangement.
1. An optical interconnection arrangement for transmitting high speed data signals, the arrangement comprising:
a transmitting component associated with a first processing node for converting an electrical high speed data signal into an optical data signal;
an optical transmission channel coupled to the output of the transmitting component; and
a receiving component associated with a second processing node and coupled to the output of the optical transmitting channel for receiving the optical data signal and re-converting the received optical data signal into the original electrical high speed data signal, wherein
the transmitting component comprises:
a phase alignment element responsive to a plurality of N of parallel data signals and an electrical clock signal to create as an output a plurality of parallel, phase-aligned data signals;
a first optical modulator responsive to the plurality of N parallel phase-aligned data signals and a continuous wave (CW) optical signal to create a pulse amplitude modulated (PAM) optical data signal representative of the plurality of N parallel phase-aligned data signals; and
a second optical modulator responsive to the electrical clock signal and a CW optical signal to create an optical clock output signal; and
the receiving component comprises:
a first optical/electrical (O/E) conversion device responsive to the received PAM optical data signal to create an electronic version thereof;
a second O/E conversion device response to the received optical clock signal to create an electronic version thereof; and
an A/D converter responsive to the outputs of the first and second O/E conversion devices to recover the original plurality of N parallel data signals therefrom.
2. An optical arrangement as defined in claim 1 wherein the transmitting component first and second optical modulators comprise first and second Mach-Zehnder interferometers, respectively.
3. An optical arrangement as defined in claim 2 wherein the first Mach-Zehnder interferometer comprises a multi-segment interferometer.
4. An optical arrangement as defined in claim 3 wherein the first Mach-Zehnder interferometer creates a PAM-N 2 output signal from a plurality of N parallel data signals.
5. An optical arrangement as defined in claim 1 wherein
the transmitting component further comprises:
a first optical signal source operating at a first wavelength λ1 coupled to the input of the first optical modulator;
a second optical signal source operating at a second wavelength λ2 coupled to the input of the second optical modulator; and
an optical multiplexer for coupling the optical output signals from the first and second optical modulators onto a single optical output signal path; and
the receiving component further comprises:
an optical demultiplexer for separating the PAM data signal propagating at wavelength λ1 from the optical clock signal propagating at wavelength λ2, and coupling each signal into a separate optical signal path.
6. An optical arrangement as defined in claim 1 wherein
the transmitting component further comprises:
an optical source operating at a wavelength λ1; and
an optical splitter for directing a first portion of the output from the optical source to the optical input of the first optical modulator and a second portion of the output from the optical source to the optical input of the second optical modulator; and
the optical transmission channel comprises a pair of optical fibers, a first fiber supporting the propagation of the PAM optical data signal and a second fiber supporting the propagation of the optical clock signal.
7. An optical arrangement as defined in claim 1 wherein the second optical modulator further comprises an optical clock distribution arrangement for dispersing a plurality of frequency-locked optical clock signals across the first processing node.
8. An optical arrangement as defined in claim 7 wherein the optical clock distribution arrangement comprises an optical splitter coupled to the output of the second optical modulator, wherein the optical splitter comprises a plurality of branching waveguides for dispersing the plurality of frequency-locked optical clock signals across the first processing node.
9. An optical arrangement as defined in claim 7 wherein the second optical modulator further comprises a second CW optical input signal source for utilization as a back-up source upon recognition of a failure of the original CW source.
10. An optical arrangement as defined in claim 1 wherein the first optical modulator further comprises a pair of CW optical input signal sources for providing the optical signal thereto, wherein a second CW optical input signal source of said pair is utilized as a back-up source upon recognition of a failure of a first CW optical input signal source of said pair of CW optical input signal sources.