Coherent Optical Receiver With Feedback Polarization Control
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Solution Overview
Problem
Optical communication devices face issues with coherent detection due to random deflection of the state of polarization (SOP) of local oscillator (LO) light during transmission, leading to incomplete reception of signal light.
Innovation Solution
A coherent optical receiver with a polarization control component, including a waveguide-type half-wave plate and feedback control circuit, continuously adjusts the SOP of LO light to ensure equal optical power in both channels, using a feedback mechanism to stabilize the SOP and enable continuous tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LO light is transmitted via optical fibers, then signal transmission is achieved, but random deflection of SOP occurs causing coherent detection failure
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the SOP of LO light before it enters the optical fiber transmission channel. The polarization control component (including half-wave plate and polarization beam splitting device) is positioned before the fiber input to proactively compensate for expected SOP deflection, ensuring that the LO light maintains proper polarization state throughout transmission for reliable coherent detection
Solution Approach 2:
The patent implements feedback control by using the detected optical power difference between two channels as a feedback signal. The feedback control circuit continuously monitors this difference and dynamically adjusts the voltage applied to the half-wave plate to maintain equal optical power in both channels, thereby stabilizing the SOP against random deflections during transmission
2Reliability
If polarization control component adjusts SOP dynamically, then coherent detection is enabled, but device complexity increases
Solution Approach 1:
The patent replaces mechanical polarization control (such as manually adjustable waveplates or rotating polarizers) with an electrically controlled waveguide-type half-wave plate. This electro-optic device uses voltage-controlled refractive index changes to adjust SOP dynamically without mechanical moving parts, reducing complexity while maintaining coherent detection capability
Solution Approach 2:
The polarization control component serves multiple functions: it adjusts SOP of LO light, balances optical power between channels, and provides feedback control. By integrating these functions into a single compact module with the waveguide-type half-wave plate and polarization beam splitting device, the patent reduces overall device complexity while achieving reliable coherent detection
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 solution ensures stable coherent detection by maintaining equal optical power in both channels of LO light, allowing continuous adjustment and preventing random deflection, thus enhancing the reliability of signal reception.
Implementation Method 1
The half-wave plate device is configured to, driven by a first voltage loaded by the feedback control circuit, deflect a state of polarization of received local oscillator light, where an azimuth of the half-wave plate device can rotate continuously under driving of a voltage within a target range of the voltage
Implementation Method 2
The first polarization beam splitting device is configured to decompose received signal light into two channels of signal light. The second polarization beam splitting device is configured to decompose the received local oscillator light into two channels of local oscillator light
Implementation Method 3
The frequency mixing component is configured to mix the two channels of signal light output by the first polarization beam splitting device and the two channels of local oscillator light output by the polarization control component
Implementation Method 4
The photoelectric detection component is configured to convert a mixed optical signal output by the frequency mixing component into an electrical signal
Data Source
AI summary
A coherent optical receiver, and an optical communication device and system, and relates to the field of optical communication. A polarization control component in the coherent optical receiver can deflect, driven by a feedback control circuit, a state of polarization of local oscillator light, and decompose the local oscillator light into two channels of light having equal or similar optical power. Therefore, the state of polarization of the local oscillator light is not deflected randomly and thereby coherent detection is not affected. Moreover, an azimuth of a half-wave plate device in the polarization control component can be deflected continuously, allowing continuous tracking and adjustment for the state of polarization of the local oscillator light.