Optical Phase Modulator With Alternating PN and PNPN Junctions
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Solution Overview
Problem
Optical phase modulators with PN junctions face challenges in maintaining effective refractive index while minimizing modulation loss due to incomplete carrier discharge and absorption by remaining carriers when a reverse bias voltage is applied.
Innovation Solution
The optical phase modulator features a rib part with alternating PN and PNPN junctions in cross-sections orthogonal to the extending direction, connected by slab portions of varying doping types, ensuring complete carrier discharge and reducing modulation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reverse bias voltage is applied to the PN junction, then the depletion layer expands and effective refractive index is maintained, but carrier discharge becomes incomplete and modulation loss increases due to remaining carriers
Solution Approach 1:
The optical waveguide is divided into multiple regions with different doping types (N-type and P-type) arranged alternately. This segmentation creates multiple depletion layers that work together to achieve complete carrier discharge while maintaining the effective refractive index, thereby reducing modulation loss.
Solution Approach 2:
Different regions of the optical waveguide are assigned different doping characteristics (N-type or P-type) to create localized depletion layers. This local quality differentiation ensures that carriers are discharged completely in each region while maintaining the overall effective refractive index needed for optical modulation.
2Loss of energy
If slab portions are added to connect rib portions, then device complexity increases, but carrier discharge completeness improves and modulation loss decreases
Solution Approach 1:
The slab portions are merged with the rib portions to form an integrated doping structure. This merging allows the slab and rib portions to work together as a unified system for carrier discharge, reducing modulation loss without requiring separate, independent components that would increase complexity.
Solution Approach 2:
The slab and rib portions serve multiple functions: they provide both the structural framework for the optical waveguide and the doping regions for carrier discharge. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving complete carrier discharge.
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 configuration maintains the effective refractive index and suppresses modulation loss by expanding depletion layers effectively, enhancing phase change and reducing carrier absorption.
Implementation Method 1
expanding depletion layers effectively
Implementation Method 2
ensuring complete carrier discharge
Implementation Method 3
Optical phase modulator having a rib part
Data Source
AI summary
An optical phase modulator includes a rib part extending in an extending direction. The rib part includes an N-type first rib portion and a P-type second rib portion arranged in a width direction to have a PN junction therebetween along the extending direction. An N-type first slab portion is connected to the first rib portion and a P-type second slab portion is connected to the second rib portion to provide a PN structure with the rib part in a cross-section having a normal direction along the extending direction. A P-type third slab portion is connected to the first rib portion and an N-type fourth slab portion is connected to the second rib portion to have a PNPN structure with the rib part in a cross-section having a normal direction along the extending direction. The PN structure and the PNPN structure are alternately disposed in the extending direction.