Coherent Optical Receiver Tunable Local Oscillator Wavemeter
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Solution Overview
Problem
Current passive optical network (PON) systems face challenges in supporting high data rates without increasing ONU costs and power consumption, particularly due to the need for wavelength stabilization and temperature control in coherent optical receivers, which are costly and inefficient.
Innovation Solution
A coherent optical receiver with a tunable local oscillator and wavemeter is used to track the wavelengths of upstream optical signals from ONUs, allowing the local oscillator to remain aligned without temperature control, using a wavemeter to rapidly and accurately determine wavelengths and adjust the local oscillator signal, thereby supporting a wide range of wavelengths and dynamic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wavelength stabilization and temperature control mechanisms are used in coherent optical receivers, then alignment accuracy with transmitter wavelengths is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical wavelength stabilization mechanisms (temperature control, wavelength locking circuits) with an optical solution using a wavemeter to measure the transmitter wavelength and a tunable local oscillator to match it. This substitution eliminates complex mechanical and thermal control systems while achieving the same alignment accuracy through optical measurement and tuning.
2Stability of the object's composition
If temperature control mechanisms are used to stabilize transmitter wavelengths, then wavelength drift is reduced, but power consumption increases
Solution Approach 1:
The patent enables the receiver to independently adapt to the transmitter's wavelength by using a wavemeter to measure the actual wavelength and a tunable local oscillator to match it. This eliminates the need for the transmitter to actively stabilize its wavelength through power-consuming temperature control, as the receiver automatically compensates for any drift.
3Device complexity
If a fixed wavelength local oscillator is used, then device complexity is minimized, but adaptability to drifting transmitter wavelengths is reduced
Solution Approach 1:
The patent transforms the static, fixed-wavelength local oscillator into a dynamic, tunable component that can adapt its wavelength in real-time. The local oscillator is controlled by the wavemeter to continuously track and match the transmitter wavelength, providing adaptability without significant complexity increase.
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
This solution enables cost-effective and efficient coherent optical reception in PON systems, allowing ONUs to operate without costly wavelength control mechanisms, supporting high data rates while minimizing power consumption and maintaining alignment with drifting transmitter wavelengths.
Implementation Method 1
The wavemeter includes a set of interferometers, wherein one of the interferometers has a path length difference corresponding to a free spectral range approximately matching or exceeding a drift range of the upstream optical signal
Implementation Method 2
a coherent optical receiver frontend configured to receive the upstream optical signal and the local oscillator signal and provide an electrical signal
Data Source
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AI summary
Various example embodiments presented herein may be configured to support a passive optical network, PON, including an optical line terminal, OLT, and a set of optical network units, ONUs, where the OLT includes a coherent optical receiver configured to support reception of upstream optical bursts by the ONUs based on use of a wavemeter to control tuning of a local oscillator to track the wavelengths of the upstream optical bursts from the ONUs. In the coherent optical receiver, the local oscillator may be configured to provide a local oscillator signal for mixing with an upstream optical signal of an ONU and the wavemeter may be configured to determine a wavelength of the upstream optical signal of the ONU and instruct the local oscillator to tune the local oscillator signal to the wavelength of the upstream optical signal of the ONU. The coherent optical receiver may be used in other contexts.