Coherent-Lite Transceiver Eliminates DSP for 400G Optical Links
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Solution Overview
Problem
Existing transceivers for short reach optics are too expensive and power hungry, making them unsuitable for intra-datacenter applications, and require high-speed digital signal processing and high-resolution converters.
Innovation Solution
A power-efficient 'coherent-lite' transceiver that eliminates the need for high-speed digital signal processing and high-resolution converters by using dual-polarization in-phase and quadrature modulation, optical polarization controllers, and circulators to achieve coherent detection without digital signal processors, enabling efficient data transmission over 10 km.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coherent detection with digital signal processing is used, then spectral efficiency and sensitivity are improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts and removes the digital signal processing components from the coherent detection system, creating a 'coherent-lite' transceiver that performs coherent detection without requiring complex DSP algorithms, thereby reducing device complexity while maintaining core coherent detection benefits
Solution Approach 2:
The invention replaces expensive, power-hungry DSP components with simpler, more cost-effective optical processing elements, making coherent detection accessible for short-reach intra-datacenter applications where full coherent systems are prohibitively expensive
2Productivity
If high-order modulation is used, then spectral efficiency is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent substitutes complex electrical digital signal processing with optical domain processing, using optical polarisation controllers and coherent detection to achieve high-order modulation benefits without the associated electrical processing complexity and power consumption
3Reliability
If DSP components are used, then transmission reliability is improved, but power consumption and cost increase
Solution Approach 1:
The patent removes the power-consuming DSP components from the system while maintaining transmission reliability through optical domain processing, demonstrating that coherent detection can achieve reliable short-reach transmission without expensive and power-hungry digital signal processing hardware
Solution Approach 2:
The optical polarisation controllers and coherent detection system perform signal processing functions autonomously in the optical domain, eliminating the need for external DSP processing and reducing overall system power consumption while maintaining reliability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The coherent-lite transceiver achieves 50 Gbaud DP-16QAM data rates of 400 Gb/s over 10 km with reduced power consumption and cost, eliminating the need for expensive digital signal processing components, while maintaining high spectral efficiency and error correction below the KP4 FEC threshold.
Implementation Method 1
a laser operative to generate a continuous wavelength
Implementation Method 2
a power splitter operative to receive the continuous wavelength from the laser and to split the continuous wavelength into a first portion and a second portion
Implementation Method 3
a dual-polarization inphase and quadrature modulator, DP-IQM, operative to receive the first portion of the continuous wavelength from the power splitter and to modulate the first portion of the continuous wavelength according to a modulation format
Implementation Method 4
a first optical polarization controller, PC, operative to receive the second unmodulated signal from the first circulator (C1, C3), and to adjust a polarization state of the second unmodulated signal
Implementation Method 5
a first circulator (C1, C3) operative to receive the first modulated signal from the DP-IQM and to transmit the first modulated signal through a full-duplex fiber
Implementation Method 6
a dual-polarization coherent receiver, DP-CRx, operative to receive, through a signal port, the polarization state adjusted modulated signal and, through a local oscillator port, the polarization state adjusted unmodulated signal, the DP-CRx performing coherent detection of modulating information
Implementation Method 7
the 90° hybrid receiving the polarization state adjusted modulated signal and the polarization state adjusted unmodulated signal through the signal port and the local oscillator port respectively, and the four balanced photodiodes operative to output the four electrical output signals
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(e)
AI summary
The disclosure relates to a transceiver operative to transmit and receive optical signals. The transceiver comprises a laser, a power splitter, a dual-polarization in-phase and quadrature modulator, DP-IQM, a first circulator (C1, C3), a second circulator (C2, C4), a first optical polarization controller, PC, a second optical polarization controller and a dual-polarization coherent receiver, DP-CRx. There is provided a system comprising a first transceiver and a second transceiver as described previously. The transceiver requires neither high speed DSP nor high resolution data converters to achieve 50 Gbaud DP-16QAM, DP standing for dual polarization and QAM standing for quadrature amplitude modulation, yielding 400 Gb/s over 10 km below the 2.2×10-4 KP4 forward error correction (FEC) threshold.