Optical Transmission Module Using Logic Circuit for PAM4 Modulation
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Solution Overview
Problem
Existing optical transmission modules require dedicated ICs to convert binary electric signals to multi-level electric signals for PAM4 modulation, leading to increased size and power consumption.
Innovation Solution
An optical transmission module that uses a light source and EA modulators arranged in series, with an arithmetic logic circuit to perform logic operations on binary electrical signals, eliminating the need for multi-level electric signal conversion by directly generating PAM4 optical modulation signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dedicated IC is used to convert binary electric signals to multi-level electric signals, then PAM4 modulation can be achieved, but module size increases
Solution Approach 1:
The patent removes the dedicated IC component from the system by implementing the modulation logic directly in the control circuit. The control circuit performs binary-to-multi-level signal conversion and PAM4 modulation functions that previously required a separate dedicated IC, thereby reducing module size while maintaining PAM4 modulation capability.
Solution Approach 2:
The patent combines the functions of the dedicated IC (signal conversion and modulation control) with the existing control circuit. By merging these functions into a single integrated control unit, the module size is reduced and component count is decreased while preserving the PAM4 modulation functionality.
2Adaptability or versatility
If dedicated IC is used to convert binary electric signals to multi-level electric signals, then PAM4 modulation can be achieved, but power consumption increases
Solution Approach 1:
The patent eliminates the dedicated IC component that consumed additional power. By implementing the modulation functions in the existing control circuit, the system removes the power consumption associated with the dedicated IC while maintaining PAM4 modulation capability.
Solution Approach 2:
The patent merges the power-consuming dedicated IC functions into the existing control circuit, which already has power supply infrastructure. This consolidation reduces overall power consumption by eliminating redundant power consumption in the dedicated IC while maintaining the same modulation functionality.
3Adaptability or versatility
If multiple modulation parts with different extinction ratios are arranged in series, then PAM4 optical signals can be generated, but device complexity increases
Solution Approach 1:
Instead of using multiple modulation parts with different extinction ratios arranged in series, the patent inverts the approach by using a single modulation part with controlled binary signals. The control circuit generates multiple binary signals with different weights (1, 2, 4) that are applied to the same modulation part, achieving PAM4 signals through signal weighting rather than through multiple modulation stages with different extinction ratios.
Solution Approach 2:
The patent changes the control parameter from extinction ratio of multiple modulation parts to signal weight of binary control signals. By varying the weight of binary signals (1, 2, 4) applied to a single modulation part, the system achieves PAM4 modulation without requiring multiple modulation parts with different extinction ratios, thereby reducing device complexity.
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 reduces module size and power consumption while enabling efficient PAM4 modulation without the need for complex signal conversion, resulting in more reliable and compact optical transmission.
Implementation Method 1
The EA modulator controls output intensity of incident light by utilizing a shift of an optical absorption edge of the semiconductor quantum well structure to longer wavelength in response to application of a voltage to the semiconductor quantum well structure to change an amount of absorption of the incident light in the semiconductor quantum well structure
Data Source
AI summary
Provided is an optical transmission module which can generate PAM4 optical modulation signals without converting a plurality of binary electric signals to a multi-level electric signal. An optical transmission module (200) comprising: a light source (60) for emitting continuous waveform (CW) light; optical modulators (51,52,53) arranged in series with a path of the CW light configured to modulate the CW light by switching relatively large absorption and relatively small absorption of the optical modulators in response to a modulation signal applied to the respective optical modulators; and an arithmetic logic circuit (100) configured to receive a plurality of binary electrical signals, and then to perform logic operation on the plurality of binary electrical signals for generating a new plurality of binary electrical signals, wherein each of the new plurality of binary electrical signals is applied to the respective optical modulators as the modulation signal.