Coherent Optical Receiver With Subband ADC Conversion
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Solution Overview
Problem
Optical receiving devices require broadband and high sampling rate analog-digital converters to handle multiplexed optical signals, leading to issues like spurious due to interleaving.
Innovation Solution
An optical receiving device that includes an optical coherent detecting unit, an analog signal separating unit, an analog-digital converting unit, a channel separating unit, and a channel individual demodulating unit, which branches and frequency-converts analog signals to a manageable frequency range, allowing analog-digital conversion without the need for a broadband and high sampling rate ADC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a broadband and high sampling rate analog-digital converter is used to handle multiplexed optical signals, then the bandwidth and sampling rate requirements are met, but spurious issues occur due to interleaving
Solution Approach 1:
The patent divides the broadband optical signal into multiple narrowband frequency subbands using optical filters. Each subband is then converted to a separate electrical signal that can be processed by standard-speed ADCs without causing spurious interleaving effects. This segmentation approach allows handling of wide bandwidth signals while avoiding the harmful effects of high-speed ADC interleving.
Solution Approach 2:
The patent introduces optical local oscillators and optical mixers as intermediary components to down-convert the high-frequency optical signals to lower intermediate frequencies before electrical conversion. This intermediary optical processing stage enables the use of lower-speed ADCs while maintaining the ability to handle broadband signals.
2Speed
If a broadband and high sampling rate analog-digital converter is used, then the bandwidth requirement is met, but the device complexity and cost increase
Solution Approach 1:
The broadband optical signal is segmented into multiple narrowband frequency channels using optical filtering. Each channel is then processed by a separate, lower-complexity ADC operating at reduced sampling rates. This segmentation transforms one high-complexity ADC requirement into multiple lower-complexity ADCs, reducing overall system complexity and cost.
Solution Approach 2:
The patent replaces the electrical processing approach (single high-speed ADC) with an optical processing approach (optical filtering, mixing, and frequency conversion) followed by multiple lower-speed ADCs. This substitution of electrical mechanics with optical mechanics enables bandwidth handling with reduced device complexity.
3Adaptability or versatility
If frequency multiplication is performed to accommodate multiple heterogeneous services, then service capacity increases, but the required bandwidth and sampling rate increase leading to spurious issues
Solution Approach 1:
The patent segments the multiplexed optical signal containing multiple heterogeneous services into separate frequency subbands. Each subband corresponding to a specific service is then independently converted to electrical signals using standard-speed ADCs. This segmentation enables accommodation of multiple services while avoiding spurious effects that would occur with direct high-speed conversion of the entire multiplexed signal.
Solution Approach 2:
The patent applies different processing characteristics to different frequency subbands corresponding to different services. Each service channel is processed with appropriate filtering and frequency conversion tailored to its specific requirements, enabling heterogeneous service accommodation while maintaining signal integrity and avoiding spurious effects.
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
Enables efficient analog-digital conversion of multiplexed optical signals without the need for a broadband and high sampling rate ADC, reducing spurious issues and maintaining signal integrity.
Implementation Method 1
the optical coherent detecting unit causes an optical signal in which a plurality of channels is frequency-multiplexed to interfere with single interference light and performs coherent detection
Implementation Method 2
performs coherent detection
Data Source
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AI summary
An optical receiving device includes an optical coherent detecting unit (110) to cause an optical signal in which a plurality of channels is frequency-multiplexed to interfere with single interference light and perform coherent detection, and output an analog signal, an analog signal separating unit (130) to branch the analog signal from the optical coherent detecting unit (110) by the number of branches of N (N is a natural number of 2 or more) in a frequency domain, and output analog signals branched in the frequency domain as analog signals each of which is frequency-converted into a frequency equal to or lower than a set frequency, and an analog-digital converting unit (300) to perform analog-digital conversion on each of the analog signals branched by the analog signal separating unit (130) and converted into a low frequency, and output resultant signals as digital signals.