Optical Isolator Offset Alignment in Coaxial TOSA
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Solution Overview
Problem
The miniaturization of optical transceiver modules poses challenges in achieving precise alignment between optical fibers and laser packages due to spatial shifts induced by optical isolators, leading to signal losses and reduced transmission efficiency.
Innovation Solution
The laser and lens within the laser package are positioned with a geometric offset based on the light shifting characteristics of the optical isolator to compensate for these shifts, ensuring accurate alignment and improved optical transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical isolator is added to prevent back reflection, then laser light protection is improved, but alignment precision deteriorates due to spatial shifts
Solution Approach 1:
The patent applies preliminary anti-action by pre-positioning the optical isolator at a specific location within the laser package that anticipates and counteracts the spatial shift effect. The isolator is placed such that its optical axis is offset from the laser diode axis by a predetermined amount that exactly compensates for the isolator-induced spatial shift, thereby preventing misalignment before it occurs.
Solution Approach 2:
The patent changes the positional parameter of the optical isolator within the laser package. Specifically, the isolator is positioned with a controlled offset from the laser diode, and the package itself is offset from the optical fiber receptacle. This parameter change in positioning transforms the harmful spatial shift effect into a compensatory mechanism that maintains alignment.
2Volume of moving object
If transceiver module size is reduced, then miniaturization is achieved, but manufacturing tolerances become more difficult to achieve
Solution Approach 1:
The patent changes the dimensional parameters of the laser package by introducing controlled offsets in the positioning of internal components. The optical isolator is placed at a specific offset position within the compact laser package, and the entire package is offset from the optical fiber receptacle. These parameter changes enable the system to maintain alignment precision despite the reduced overall size and tighter manufacturing tolerances.
Data Source
AI summary
A coaxial transmitter optical subassembly (TOSA) with optical isolator alignment correction may be used in an optical transceiver for transmitting an optical signal at a channel wavelength. The coaxial TOSA includes an optical fiber coupling receptacle extending from a laser package. The laser package may include a laser diode and a lens to focus laser light emitted from the laser diode onto an optical fiber. The laser diode and lens are aligned along a first longitudinal axis of the laser package parallel to a transmission path of the laser light. An optical isolator located in the transmission path is aligned along a second longitudinal axis of the laser package. The second longitudinal axis is coincident with a centerline of the laser package, and the first longitudinal axis is offset from the second longitudinal axis by a predetermined offset distance to compensate for light shifting characteristics of the isolator.