Light Source Circuit Phase Control for Returning Light Suppression
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Solution Overview
Problem
The existing light source circuits with branched optical waveguides face instability due to returning light, which affects the operation of semiconductor laser diodes, and existing solutions require complex magnetic fields or precise microfabrication to reduce reflection, making them costly and difficult to integrate on silicon substrates.
Innovation Solution
A light source circuit with a phase control structure that adjusts the light path lengths between optical branch sections to anti-phase the reflection light, effectively inhibiting returning light by setting the absolute difference in light path lengths to (¼+i/2) times the wavelength, where i is an integer, using a dynamic phase control mechanism such as a micro heater or phase modulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-stage branched optical waveguide is used to distribute light to multiple optical devices, then the light distribution capability is improved, but the returning light intensity increases due to multiple branch sections
Solution Approach 1:
The patent converts the harmful returning light into a beneficial effect by intentionally designing the optical path length difference to be (1/4+i/2) times the wavelength. This causes reflection lights from different branch sections to interfere destructively, transforming the harmful returning light into a mechanism that actively suppresses itself through controlled interference.
Solution Approach 2:
The patent changes the optical path length parameter of the waveguides connecting branch sections to a specific value ((1/4+i/2) times the wavelength). This parameter change transforms the returning light from a harmful effect into a controlled interference pattern that suppresses itself, allowing multi-stage branching without proportionally increasing returning light intensity.
2Object-generated harmful factors
If optical isolators using magneto-optical materials are used to inhibit returning light, then the returning light suppression is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts and eliminates the need for complex magneto-optical materials and magnetic field generation devices. By using standard silicon waveguide materials with a specifically designed optical path length, the invention achieves returning light suppression without requiring additional isolator components or magnetic field equipment.
Solution Approach 2:
The patent uses homogeneous silicon-based waveguide materials throughout the optical circuit, including the waveguides connecting branch sections. This eliminates the need to integrate heterogeneous magneto-optical materials with different physical properties, simplifying manufacturing and improving compatibility with standard silicon photonics processes.
3Adaptability or versatility
If the number of branch stages is increased to distribute light to more devices, then the light distribution versatility is improved, but the microfabrication precision requirements increase to control reflection
Solution Approach 1:
The patent converts the harmful effect of multiple reflections in multi-stage waveguides into a beneficial self-suppression mechanism. By setting the optical path length to (1/4+i/2) times the wavelength, reflection lights from multiple branch stages interfere destructively, allowing increased versatility without proportionally increasing precision requirements.
Solution Approach 2:
The patent applies preliminary design of the optical path length during the planning stage, setting it to a specific value that inherently suppresses returning light. This preliminary configuration ensures that even as the number of branch stages increases, the returning light is automatically controlled through the pre-established interference condition, reducing the need for post-fabrication adjustments.
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 stabilizes the operation of semiconductor laser diodes by significantly reducing returning light, allowing for efficient light distribution to multiple optical devices without the need for magnetic fields or high-precision microfabrication, thus enhancing the reliability and cost-effectiveness of the light source circuit.
Implementation Method 1
a light path length L1 of an optical waveguide between the optical branch section and a next-stage optical branch section or an optical device which is connected to a first output side optical waveguide extending from the optical branch section, and a light path length L2 of an optical waveguide between the optical branch section and a next-stage optical branch section or an optical device which is connected to a second output side optical waveguide are selected such that an absolute value of a difference between the light path length L1 and the light path length L2 is (1/4+i/2) times (i is 0 or a positive integer) a wavelength of the light propagated through the light source circuit
Data Source
AI summary
A light source circuit transmits light incident from a semiconductor laser source to a plurality of optical devices. At least one optical branch section is formed to branch one input-side optical waveguide at least into a first output-side optical waveguide terminal and a second output-side optical waveguide terminal. A light path length (L1) between the optical branch section and a next-stage optical branch section or the optical device is connected to the first output-side optical waveguide extending from the optical branch section and a light path length (L2) between the optical branch section and the next-stage optical branch section selected such that the absolute value of a difference between (L1) and (L2) is (¼+i/2) times (i is zero or a positive integer) the wavelength of the light transmitted through the light source circuit.