VCSEL Mode Separation for High-Entropy Random Number Generation
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Solution Overview
Problem
Existing random number generators struggle to produce high-quality random numbers at high speeds and low costs, particularly in applications requiring small size and low costs, such as encryption and gaming, where the generation rate is insufficient.
Innovation Solution
A random number generator utilizing a vertical cavity surface emitting laser (VCSEL) with a mode separator and photodetector, operating in direct modulation mode to emit two distinct laser modes of random relative strength, allowing for efficient generation of random bits by separating and detecting these modes, thereby achieving high entropy output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a VCSEL with mode suppressing component is used, then communication reliability is improved, but random number generation capability deteriorates
Solution Approach 1:
The patent segments the laser emission into two distinct modes (first laser mode and second laser mode) that can be independently detected. By removing the mode suppressing component, both modes are allowed to emit with random relative strengths, enabling parallel detection channels that increase the random number generation rate while maintaining reliability through dual-mode verification
Solution Approach 2:
The patent transitions from single-mode detection to multi-mode detection by utilizing two distinct laser modes with different propagation characteristics. This dimensional expansion in the mode space allows simultaneous detection of multiple random intensity variations, thereby increasing the entropy generation rate without sacrificing detection reliability
2Productivity
If VCSEL operates at high frequencies, then transmission rate is improved, but random number generation quality deteriorates
Solution Approach 1:
The patent introduces two separate photodetectors as intermediary detection elements, each dedicated to detecting one of the two laser modes. This intermediary detection architecture allows the system to process high-frequency VCSEL output while maintaining random number generation quality through independent detection channels that can be optimized for their specific detection tasks
Solution Approach 2:
The patent changes the detection parameter from single-intensity measurement to multi-intensity measurement by detecting the intensities of two distinct laser modes simultaneously. This parameter expansion allows the system to capture more entropy from the same high-frequency VCSEL output, maintaining random number quality even at high transmission rates
3Productivity
If mode separator is added to separate laser modes, then random number generation capability is improved, but device complexity increases
Solution Approach 1:
The patent creates a simplified copy of the detection path by using two separate photodetectors that independently detect the two laser modes without requiring complex optical coupling. This copying approach eliminates the need for sophisticated mode separation optics, reducing device complexity while maintaining the ability to generate random numbers from both modes simultaneously
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 enables fast and reliable generation of random numbers with reduced costs, leveraging the VCSEL's high-frequency capabilities and quantum mechanical properties to produce truly random sequences efficiently.
Implementation Method 1
a power source to drive the VCSEL in direct modulation mode
Implementation Method 2
the VCSEL is adapted to emit, from an emitting section into space outside of a VCSEL cavity, laser light with two distinct laser modes of random relative strength
Implementation Method 3
the mode separator is arranged to separate the two distinct laser modes from each other and to transmit one of the distinct laser modes to the photodetector
Implementation Method 4
the photodetector outputs a signal depending on the intensity of the laser light received at the photodetector via the mode separator from the VCSEL
Data Source
AI summary
Provided for herein is random number generator that includes a vertical cavity surface emitting laser, VCSEL, a mode separator and a photodetector, the random number generator further comprising a power source to drive the VCSEL in direct modulation mode. The VCSEL is adapted to emit, from an emitting section into space outside of a VCSEL cavity, laser light with two distinct laser modes of random relative strength that can propagate in a propagation direction away from the emitting section. The mode separator is arranged between the photodetector and the VCSEL in propagation direction to separate the two distinct laser modes from each other and to transmit one of the distinct laser modes to the photodetector.