Optical Interferometer Suppression of Excitation Light in Quantum Emitters
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Solution Overview
Problem
Separating excitation light from luminescence is challenging, especially for low beam powers such as single or few photons, due to similar characteristics like wavelength and polarization, which complicates signal-to-noise ratio in detection.
Innovation Solution
An excitation cancelling beam is used to destructively interfere with residual excitation light, adjusting phase and amplitude to minimize co-propagating excitation light, often passively controlled without active components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If excitation light and luminescence are both directed to a detector, then detection of luminescence is possible, but signal-to-noise ratio decreases due to presence of excitation beam
Solution Approach 1:
The patent applies preliminary anti-action by generating an excitation cancelling beam that is configured to destructively interfere with the excitation beam before both reach the detector. This cancelling beam is created in advance with appropriate amplitude and phase characteristics to counteract the harmful excitation light, thereby improving signal-to-noise ratio without losing the luminescence signal
Solution Approach 2:
The patent converts the harmful excitation beam into a beneficial effect by using it as a reference to create the excitation cancelling beam. The excitation beam's own characteristics (amplitude, phase, polarization) are utilized to generate an opposing beam that, when combined, produces destructive interference that eliminates the harmful excitation light while preserving the luminescence detection capability
2Productivity
If excitation light and luminescence have similar characteristics, then luminescence generation is efficient, but separation of beams becomes difficult
Solution Approach 1:
The patent introduces an intermediary element - the excitation cancelling beam - that mediates between the excitation beam and the detector. This intermediary beam has similar characteristics to the excitation beam (allowing it to effectively cancel the excitation light) but is controlled to interfere destructively only with the excitation component, thereby enabling beam separation without compromising luminescence generation efficiency
Solution Approach 2:
The patent applies parameter changes by precisely controlling the amplitude and phase parameters of the excitation cancelling beam. By adjusting these parameters, the system achieves destructive interference with the excitation beam while maintaining constructive interference or neutral interaction with the luminescence, thereby solving the beam separation difficulty without reducing luminescence generation efficiency
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
Enhances signal-to-noise ratio by significantly reducing residual excitation light, particularly beneficial for single-photon detection applications.
Implementation Method 1
A relative phase of the residual excitation beam and the excitation cancelling beam is selected so that the residual excitation beam and the excitation cancelling beam interfere destructively
Data Source
AI summary
Excitation used to produce luminescence is cancelled using interference with an excitation cancelling beam by controlling or setting a phase difference. An excitation beam and an excitation cancelling beam are produced from a common source and the excitation beam directed quantum light emitter to produce luminescence. A residual excitation beam and the excitation cancelling beam are coupled to interfere destructively so that the luminescence is available for detection or otherwise without substantial portions of the excitation beam.