Optical D/A Converter with Coherent Channel Segmentation
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Solution Overview
Problem
Existing optical digital-to-analog (D/A) converters suffer from increased noise due to voltage excursions in control signals, particularly at high operating speeds, making them inadequate for high-speed applications.
Innovation Solution
An optical D/A converter design that splits an input coherent optical carrier into multiple mutually coherent carriers, uses selector switches to pass or interrupt carriers based on pattern bits, and an amplitude and phase offset stage to adjust the carriers' amplitudes and phases, recombining them to produce an optical output signal with reduced noise susceptibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the operating speed of the optical D/A converter is increased, then the signal processing capability is improved, but the noise due to voltage excursions increases dramatically
Solution Approach 1:
The patent segments the control signal generation into multiple independent channels, each handling a specific bit of the digital input. By dividing the single control signal path into N separate channels, each channel operates at a lower speed and generates less voltage excursion noise. The segmented control signals are then combined through coherent addition to achieve the high-speed output without the noise problems of a single high-speed channel.
2Speed
If the operating speed of the optical D/A converter is increased, then the signal processing capability is improved, but the susceptibility to control signal voltage excursions worsens
Solution Approach 1:
The system divides the high-speed conversion task into N parallel lower-speed channels. Each channel processes a portion of the digital input at a manageable speed, reducing voltage excursions. The segmented approach allows each channel to operate reliably without excessive susceptibility to voltage excursions, while the overall system achieves high-speed performance through coherent combination.
3Device complexity
If a single-channel high-speed D/A converter is used, then the device complexity is reduced, but the noise performance deteriorates
Solution Approach 1:
The patent employs N parallel D/A converter channels instead of a single channel. While this increases the number of components, each channel operates at a lower speed and generates less noise. The segmented structure trades moderate complexity for significantly improved noise performance, as the noise from each channel is lower and can be coherently combined to produce a clean high-speed output.
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 effectively reduces noise from control signal voltage excursions, enabling the optical D/A converter to operate with less noise and be more suitable for high-speed applications by dividing modulation into two stages, minimizing the impact of rapid pattern bit changes and slow control signal variations.
Implementation Method 1
a splitter configured to receive and split an input coherent optical carrier into a plurality of mutually coherent optical carriers
Implementation Method 2
an amplitude and phase offset stage coupled to the switching stage and including a corresponding plurality of amplitude and phase offset units configured to offset amplitudes or phases of passed ones of the plurality of mutually coherent optical carriers
Data Source
AI summary
An optical digital-to-analog (D/A) converter and a method of optically converting digital data into analog form. In one embodiment, the optical D/A converter includes: (1) a splitter configured to receive and split an input coherent optical carrier into a plurality of mutually coherent optical carriers, (2) a switching stage coupled to the splitter and including a corresponding plurality of selector switches configured to pass or interrupt selected ones of the plurality of coherent optical carriers responsive to pattern bits, (3) an amplitude and phase offset stage coupled to the switching stage and including a corresponding plurality of amplitude and phase offset units configured to offset amplitudes or phases of passed ones of the plurality of mutually coherent optical carriers responsive to offset signals and (4) a combiner coupled to the amplitude and phase offset stage and configured to recombine the mutually coherent optical carriers to yield an optical output signal.