Optical Transmitter Seeding for Random-Phase Quantum Pulses
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Solution Overview
Problem
Conventional QKD and QRNG systems face limitations in pulse generation rate due to phase correlation between optical pulses caused by residual photons in the laser cavity, requiring prolonged downtime and complex laser driving conditions, which restricts performance and stability.
Innovation Solution
An optical transmitter design that incorporates a light source for spontaneous emission photons into the laser cavity, seeding each pulse with random phases, allowing higher pulse repetition rates and reducing downtime, and utilizing phase randomness for QRNG operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laser is driven below the lasing threshold for prolonged downtime to ensure residual photons escape, then phase correlation between pulses is reduced, but the maximum clock rate and pulse generation rate are restricted
Solution Approach 1:
The patent extracts the harmful residual photons from the laser cavity by using an optical pump to clear out remaining photons between pulse generations. This active removal mechanism ensures that each new pulse is seeded only by spontaneous emission photons rather than inheriting phase from previous pulses, thereby maintaining phase randomness without requiring prolonged downtime and enabling high pulse generation rates.
2Productivity
If the bias current of the laser is increased to improve pulse generation speed, then productivity increases, but phase correlation occurs between pulses
Solution Approach 1:
The patent introduces an optical pump as an intermediary component that actively manages the photon population in the laser cavity. This mediator clears residual photons between pulses, allowing the laser to operate at high bias currents for fast pulse generation while maintaining phase randomness. The optical pump acts as a control mechanism that decouples the trade-off between speed and phase quality.
3Productivity
If the laser operates at high clock rates to improve productivity, then pulse generation rate increases, but residual photons cause phase correlation
Solution Approach 1:
The patent applies preliminary action by using the optical pump to clear residual photons from the laser cavity before each new pulse generation event. This preparatory cleaning action ensures that the cavity is ready to receive only spontaneous emission photons for seeding the next pulse, maintaining phase randomness even at high clock rates where residual photons would normally persist.
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 high-speed, robust operation of QKD and QRNG systems by eliminating phase correlation and enabling real-time monitoring of quantum randomness, improving stability and performance beyond current state-of-the-art.
Implementation Method 1
a light source configured to emit photons via spontaneous emission, the light source being coupled into the cavity of the laser such that the photons emitted by the light source will seed the pulses of light generated by the laser
Data Source
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AI summary
An optical transmitter comprising: a laser source configured to generate pulses of light for output by the transmitter; a pump for the laser source; and a light source configured to emit photons via spontaneous emission, the light source being coupled into the cavity of the laser such that the photons emitted by the light source will seed the pulses of light generated by the laser, each successive pulse having a random phase.