Thin Optical Isolator Polarization Layout for Handheld Lasers
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Solution Overview
Problem
Existing optical isolators are too thick for applications in handheld devices, such as those incorporating semiconductor lasers, while maintaining the required level of optical isolation and causing increased insertion loss.
Innovation Solution
A reduced thickness optical isolator design using a garnet with specific polarization rotation angles and orientations of polarizer and analyzer, allowing for effective unidirectional signal transmission and reflection blocking, even with increased insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional thickness optical isolator is used, then optical isolation performance is maintained, but the device thickness increases and insertion loss increases
Solution Approach 1:
The patent changes the polarization rotation angle parameter from the conventional 45 degrees to a reduced angle between 10-30 degrees. This parameter modification allows the use of thinner garnet layers (reducing device thickness) while maintaining adequate optical isolation performance through the optimized angle that balances isolation effectiveness with reduced material requirements.
Solution Approach 2:
The patent introduces adjustable polarization rotation angles that can be dynamically optimized based on specific application requirements. By making the rotation angle a variable parameter rather than a fixed 45-degree value, the system can adapt to different thickness constraints and performance requirements, enabling thinner device designs.
2Length of stationary object
If a reduced thickness optical isolator is used, then device thickness is reduced for handheld applications, but insertion loss increases
Solution Approach 1:
The patent optimizes the polarization rotation angle parameter to a specific range (10-30 degrees) that minimizes insertion loss while enabling reduced thickness. This parameter optimization ensures that the reduced thickness design does not excessively compromise signal transmission efficiency, balancing thickness reduction with acceptable energy loss.
3Length of stationary object
If a reduced thickness optical isolator is used, then device thickness is reduced, but optical isolation performance may be compromised
Solution Approach 1:
The patent modifies the polarization rotation angle from the conventional 45 degrees to a reduced range of 10-30 degrees. This parameter change enables the use of thinner garnet layers while maintaining sufficient optical isolation performance, as the optimized angle provides adequate reflection blocking with reduced material thickness.
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
Achieves the desired optical isolation with reduced thickness, suitable for handheld devices, by rotating polarization angles to block reflections effectively, albeit with increased insertion loss.
Implementation Method 1
A optical isolator 2, an exploded view of which is shown in FIG. 1A, is based on a Faraday rotator or garnet 14 sandwiched between a first polarizer 10 and a second polarizer or analyzer 18
Data Source
AI summary
In an optical isolator, a garnet rotates a polarization of an optical signal input into the garnet via a polarizer from an optical signal source in a first direction and outputs it as a first garnet output optical signal to an analyzer which outputs it as a first analyzer output optical signal. A difference (D) between a polarization of the first garnet output optical signal and a polarization axis of the analyzer is 10°≤D<84°. The analyzer outputs a reflection of the first analyzer output optical signal as a second analyzer output optical signal to the garnet which rotates a polarization thereof in the first direction and outputs it to the polarizer as a second garnet output optical signal. The polarizer blocks ≥25 dB of the second garnet output optical signal that is received from the garnet and output to the optical signal source.