Optical Pulse Modulation with Delay-Line Reflection Blocking
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Solution Overview
Problem
Conventional optical isolators are not compatible with photonic integrated circuits, making it difficult to protect lasers from back reflections in quantum communication systems, which are essential for maintaining stability and scalability.
Innovation Solution
An optical device with an intensity controlling element that modulates light intensity between a light source and an optical component, using a delay line to prevent back reflections by switching between 'on' and 'off' states based on the roundtrip time, ensuring the reflected light is blocked or attenuated, thereby protecting the light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical isolators are used to protect lasers from back reflections, then laser stability is improved, but device compatibility with photonic integrated circuits deteriorates
Solution Approach 1:
The patent extracts the essential function of optical isolation (protecting the laser from back reflections) and implements it through a different mechanism - using an optical switch to block reflected light paths rather than relying on non-reciprocal optical elements. This allows the isolation function to be integrated into photonic circuits without requiring incompatible components.
Solution Approach 2:
The patent introduces an optical switch as an intermediary component between the laser and the optical system. This switch acts as a controllable gate that can block or allow light transmission, providing the necessary isolation function while being compatible with integrated photonic fabrication techniques.
2Volume of moving object
If compact photonic integrated circuits are implemented to improve scalability and reduce dimensions, then device size is reduced, but the ability to protect lasers from back reflections deteriorates
Solution Approach 1:
The patent merges the optical isolation function with the existing photonic integrated circuit components. The optical switch is integrated directly into the circuit architecture, combining the functions of light routing and back-reflection protection in a single compact structure, eliminating the need for separate isolator components.
Solution Approach 2:
The patent employs a dynamically controllable optical switch that can change its transmission state based on the presence of back reflections. This dynamic approach allows the system to provide protection only when needed, maintaining compact dimensions while ensuring laser stability through active control rather than passive isolation.
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 enhances the stability of the light source by preventing back reflections, enabling the development of compact, fully integrated optical transceivers for coherent optical communications and quantum communication systems, improving scalability and reducing costs.
Implementation Method 1
An intensity control element adjustable between an on-state and an off-state... The intensity control element is configured to modulate an intensity of the received optical pulse
Implementation Method 2
an optical channel characterised by an optical propagation time through the optical channel (i.e. from the first to the second port)
Implementation Method 3
a beam emitted by a laser may be partially reflected back to the laser by other optical components of an optical system
Data Source
Figure 1~2
Figure 3A~3D
Figure 4~5
AI summary
An optical device comprises a light source, an intensity control element (adjustable between an on-state and an off-state), an optical channel, and an optical component. The light source supplies an optical pulse to the intensity control element, which modulates an intensity of the received pulse and to provides the modulated pulse to the channel. The intensity of the modulated pulse is higher when the intensity control element is in the on-state than in the off-state. The optical component receives the modulated pulse from the channel. The optical intensity modulator is configured such that at least a portion of the pulse is modulated in the on-state, the leading edge of said portion exits the intensity modulator at a first time, and the intensity modulator is in the off-state at a second time which is twice the propagation time measured from to the first time.