Kerr Electro-Optical Modulator With Interface Carrier Trapping
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Solution Overview
Problem
Existing electro-optical Kerr effect modulators suffer from modulation of the phase of the electromagnetic wave being influenced by both the Kerr effect and the plasma dispersion effect, leading to degradation in performance and limited maximum modulation frequency due to variations in free carrier density and optical absorption.
Innovation Solution
Trapping free carriers at the interface between the core and optical cladding of the waveguide using ionizing radiation, followed by thermal annealing to reduce their concentration, thereby eliminating the plasma dispersion effect and chirp, and allowing pure phase modulation with higher maximum modulation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pn-type junction or pin-type structure is used in the waveguide core, then the Kerr effect enables phase modulation, but the plasma dispersion effect causes unwanted amplitude modulation and chirp
Solution Approach 1:
The patent extracts and removes free carriers from the core region where they cause harmful plasma dispersion effects. By applying ionizing radiation, free carriers are generated and then extracted/trapped at the core-cladding interface, separating them from the optical mode region. This eliminates the plasma dispersion effect while preserving the Kerr effect phase modulation capability.
Solution Approach 2:
The patent converts the harmful plasma dispersion effect into a beneficial mechanism by using ionizing radiation to generate free carriers that are then trapped at the interface. The trapped carriers create a potential well that prevents further carrier generation in the core, effectively using the carrier generation process to suppress the harmful effect.
2Ease of operation
If free carriers are present in the core, then electrical field application is enabled, but optical absorption increases causing chirp and limiting maximum modulation frequency
Solution Approach 1:
The patent extracts free carriers from the optical mode region by trapping them at the core-cladding interface using ionizing radiation. This removal of carriers from the core region reduces optical absorption and chirp while maintaining the ability to apply electrical fields for Kerr effect modulation.
Solution Approach 2:
The patent moves the free carrier population from the two-dimensional core region to the one-dimensional interface between core and cladding. This dimensional relocation concentrates carriers at the boundary where they no longer interact with the optical mode, reducing absorption losses while preserving electrical control capability.
3Reliability
If ionizing radiation is applied to trap free carriers at the interface, then plasma dispersion effect is eliminated, but free carrier concentration at interface increases
Solution Approach 1:
The patent extracts free carriers from the harmful core region and relocates them to the core-cladding interface. Although carrier concentration increases at the interface, this spatial separation removes carriers from the optical mode region, eliminating plasma dispersion effects and chirp while maintaining Kerr effect functionality.
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 method achieves pure phase modulation without significant amplitude modulation, enhancing the maximum modulation frequency and reducing optical losses by concentrating free carriers at the interface, thus improving the electro-optical modulator's performance.
Implementation Method 1
irradiate the interface with ionizing radiation so as to trap free carriers from the pn-type junction or the pin-type structure at the interface
Implementation Method 2
trap free carriers from the pn-type junction or the pin-type structure at the interface
Implementation Method 3
step c) is followed by a thermal annealing step carried out according to a thermal budget adapted to reduce the concentration of free carriers trapped at the interface
Implementation Method 4
a core, including a pn-type junction or a pin-type structure
Implementation Method 5
the variation in the density of free carriers, originating from the pn-type junction or the pin-type structure
Implementation Method 6
polarize the pn-type junction or the pin-type structure so as to apply an electric field within the core
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A method of manufacturing a Kerr effect electro-optical modulator, comprising the steps of: a) using a substrate (1); b) forming a waveguide (2) on the substrate (1) so as to guide propagation of an electromagnetic wave, the waveguide (2) comprising: - a core (20), comprising a pn-type junction or a pin-type structure; - an optical cladding (21), surrounding the core (20); the core (20) and the optical cladding (21) having an interface (I); c) irradiating the interface (I) with ionizing radiation so as to trap at the interface (I) free carriers originating from the pn-type junction or the pin-type structure; d) polarizing the pn-type junction or the pin-type structure so as to apply an electric field within the core (20).