Chirped Laser with Passive Filter for DPSK Generation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Prior art RZ-DPSK transmitters are complex, expensive, and require high power consumption due to the use of multiple optical components like LiNbO3 Mach-Zehnder interferometers, making them unsuitable for small form factor transponders.
Innovation Solution
A compact RZ-DPSK transmitter is developed using a frequency modulated source and an optical spectrum reshaper, eliminating the need for external modulators and reducing power consumption by generating DPSK signals through a directly modulated laser and a multi-cavity etalon filter, arrayed waveguide grating, or fiber Bragg grating filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple optical components (LiNbO3 Mach-Zehnder interferometers) are used to generate RZ-DPSK signals, then the signal quality and reach are improved, but the device complexity, manufacturing cost, and power consumption increase significantly
Solution Approach 1:
The patent combines multiple separate optical components (Mach-Zehnder interferometers, modulators, filters) into a single integrated laser device that performs all necessary functions internally. The laser incorporates multiple cavities with different reflectivities that work together to generate RZ-DPSK signals, eliminating the need for external modulators and complex component assemblies.
Solution Approach 2:
The laser device performs multiple functions simultaneously: it acts as the light source, the modulator, and the pulse generator. By incorporating multiple cavities with different reflectivities within a single laser structure, the device can generate both the carrier signal and the return-to-zero pulse shaping without requiring separate dedicated components for each function.
2Reliability
If multiple optical components are used for RZ-DPSK generation, then the transmission reach is extended, but the manufacturing cost and power consumption increase
Solution Approach 1:
The patent combines multiple separate optical components (Mach-Zehnder interferometers, modulators, filters) into a single integrated laser device that performs all necessary functions internally. The laser incorporates multiple cavities with different reflectivities that work together to generate RZ-DPSK signals, eliminating the need for external modulators and complex component assemblies.
Solution Approach 2:
The patent replaces expensive, complex optical components with a simpler, more cost-effective laser structure. By using standard laser fabrication techniques to create multiple cavities with different reflectivities, the solution reduces manufacturing costs while maintaining the required transmission performance of over 250 km.
3Reliability
If LiNbO3 Mach-Zehnder interferometers are used for modulation, then the DPSK signal generation is achieved, but the power consumption increases due to high power drivers
Solution Approach 1:
The laser device performs self-modulation by incorporating multiple cavities with different reflectivities within its structure. The laser automatically generates the RZ-DPSK signal through its internal cavity dynamics without requiring external high-power modulators or their associated power-consuming driver circuits. The laser's own optical fields interact within the cavities to produce the desired modulation.
Solution Approach 2:
The patent extracts the modulation function from separate external components and integrates it directly into the laser source. By removing the need for external Mach-Zehnder interferometers and modulators, the solution eliminates the power consumption associated with high-power driver circuits while maintaining the modulation performance required for DPSK signal generation.
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 extends the reach of the transmitter to over 250 km on standard single mode fiber at 10 Gb/s and 1550 nm, improving sensitivity and reducing manufacturing costs while maintaining high performance.
Implementation Method 1
the summed signal is input to a laser that produces an output having frequency modulation corresponding to the magnitude of the summed signal
Implementation Method 2
the output of the laser is transmitted through an optical spectrum reshaper (OSR)
Data Source
AI summary
Apparatus and methods for driving a transmitter to generate DNPSK signals is disclosed including generating N data streams comprising data symbols and for each of a plurality of sets of N simultaneous data symbols of the N data streams, imposing signals are on L of a plurality of signal lines, with the value of L corresponding to values of the N simultaneous data symbols. Signals on the plurality of signal lines are ANDed with a clock signal synchronized with the N data streams to produce RZ signals. The RZ signals are summed and the summed signal is input to a laser that produces an output having frequency modulation corresponding to the magnitude of the summed signal. The output of the laser is passed through an optical discriminator.