Optical Isolator Core for Non-Collimating Beams
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Solution Overview
Problem
Conventional polarization independent optical isolators fail to effectively isolate backward light for non-collimating beams, as they rely on angle differences that are insensitive in such scenarios, leading to inadequate optical isolation.
Innovation Solution
An optical isolator core comprising a first birefringent crystal, a Faraday rotator, and a second and third birefringent crystal, arranged in a parallel plate structure, which separates and rotates the polarization states of forward and backward light to ensure the backward light is laterally displaced and deviates from the forward optical path, achieving optical isolation in polarization-independent and non-collimating beam scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polarization independent optical isolator uses two birefringent crystal wedges and one Faraday rotator to change exit angles of backward light, then optical isolation is achieved for collimating beam, but the design fails to isolate backward light for non-collimating beam
Solution Approach 1:
The patent changes the key parameter from angle difference to lateral displacement. By using parallel plate structures instead of wedges, the system creates lateral displacement of backward light that is independent of beam collimation, making it effective for both collimating and non-collimating beams while maintaining optical isolation
Solution Approach 2:
The patent transitions from using angular separation (one dimension) to lateral displacement (another dimension). The parallel plate birefringent crystals produce lateral displacement of orthogonal polarization components, which is a spatial shift rather than an angular deviation, making the isolation mechanism effective for non-collimating beams where angle differences are insensitive
2Reliability
If polarization dependent isolator uses two polarizers and one Faraday rotator to block backward light, then backward light is completely isolated, but the design only allows forward light in a specific polarization state to travel through
Solution Approach 1:
The patent changes the isolation mechanism from polarization filtering to lateral displacement. By using birefringent crystals that displace orthogonal polarization components laterally in opposite directions, the system achieves isolation without requiring specific polarization states, making it polarization independent while maintaining effective backward light blocking
Solution Approach 2:
The patent extracts the polarization selection function and replaces it with a geometric displacement mechanism. Instead of using polarizers to select and block based on polarization state, the system uses parallel plate birefringent crystals to spatially separate backward light components laterally, removing the polarization dependency while maintaining isolation effectiveness
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 provides high forward coupling efficiency and low polarization-dependent loss while effectively isolating backward light, making it applicable to non-collimating beams by ensuring the backward light is rotated 90 degrees relative to the forward light and laterally displaced, thus preventing it from entering the forward optical path.
Implementation Method 1
a first birefringent crystal, a Faraday rotator, a second birefringent crystal and a third birefringent crystal that are successively arranged along a forward optical path... the first birefringent crystal is configured to separate the forward light into first crystal forward o light and first crystal forward e light
Implementation Method 2
the Faraday rotator is configured to respectively rotate, at a rotation angle alpha, a polarization direction of the first crystal forward o light and a polarization direction of the first crystal forward e light
Data Source
AI summary
An optical isolator core includes: a first birefringent crystal, a Faraday rotator, a second birefringent crystal, and a third birefringent crystal that are successively arranged along a forward optical path. In response to forward o light and forward e light successively traveling through the aforementioned optical elements, displacements of exit points of the forward o light and the forward e light with respect to an incident point are the same, and the forward o light and the forward e light are merged as exiting forward light. In response to backward o light and backward e light successively reversely traveling through the aforementioned optical element, displacements of exit points of the backward o light and the backward e light with respect to the incident point of the forward light causes the backward o light and the backward e light to deviate from the forward optical path.