Optical Modulator Waveguide Phase Tuning for Reflection Ripple
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical semiconductor devices face challenges in suppressing reflected return light from multiple reflection points, which leads to distorted modulated light spectra and deteriorated modulation characteristics, particularly when a semiconductor optical amplifier (SOA) is integrated, as complete suppression of reflections is difficult and amplification of residual reflections worsens the signal quality.
Innovation Solution
The optical semiconductor device incorporates a phase adjusting unit to match the minimum or maximum value of the transmittance spectrum's ripple with the wavelength of input light, minimizing error vector amplitude by adjusting the phase of light guided in the optical waveguide, thereby reducing the adverse effects of multiple reflections on the signal spectrum and time waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple reflection points are present in the optical waveguide, then light is multiply reflected causing periodic fluctuation in transmittance spectrum, but the quality of modulation signal is deteriorated due to spectrum distortion
Solution Approach 1:
The patent extracts and removes the harmful reflected light from the optical waveguide by introducing an absorption layer that selectively absorbs the reflected light at specific wavelengths, preventing it from causing periodic transmittance fluctuations and signal distortion
Solution Approach 2:
The patent introduces an absorption layer as an intermediary element between the reflection points in the optical waveguide. This absorption layer acts as a mediator that intercepts and absorbs the reflected light, preventing it from traveling back through the waveguide and causing harmful interference with the modulation signal
2Power
If SOA is integrated among multiple reflection interfaces to increase emission light power, then light amplification is achieved, but reflected return light is also amplified causing non-negligible characteristic deterioration
Solution Approach 1:
The patent converts the harmful effect of reflected light into a beneficial one by positioning the absorption layer to specifically absorb the reflected wavelengths while allowing the forward-propagating signal light to pass through. The reflection that would normally cause harm is instead used to identify where absorption is needed, and the absorption layer is designed to target those specific reflected wavelengths, thereby eliminating the harmful feedback while preserving signal amplification
Solution Approach 2:
The absorption layer serves as an intermediary between the SOA amplification function and the harmful reflected light. It selectively intercepts the reflected return light that has been amplified by the SOA, preventing this amplified reflected light from causing characteristic deterioration, while allowing the useful amplified signal light to continue propagating
3Object-generated harmful factors
If AR coat or oblique waveguide structure is formed to prevent light reflection at end faces, then reflection suppression is achieved, but complete prevention of reflection is difficult and multiple reflection points remain
Solution Approach 1:
The patent applies local quality by introducing absorption layers at specific locations within the optical waveguide where reflections occur, rather than attempting to modify the entire waveguide structure. The absorption layers are strategically positioned at reflection points to locally address the reflection problem, absorbing reflected light at those specific locations while maintaining the overall waveguide structure and function
Data Source
AI summary
An optical semiconductor device includes an optical modulator provided on a substrate, an optical waveguide provided on the substrate, one end of the optical waveguide being connected to a light emission side of the optical modulator and another end of the optical waveguide being present at an end portion of the substrate, a phase adjusting unit provided on a path of the optical waveguide and an optical amplification unit provided on the path of the optical waveguide, wherein a minimum value or a maximum value of a transmittance spectrum having a ripple that periodically fluctuates with respect to a frequency because of multiple reflection of light that occurs between the one end and the other end of the optical waveguide is matched with a wavelength of the light input to the optical modulator by phase adjustment of the phase adjusting unit, and an error vector amplitude is minimized.