Compact Photonic Crystal Optical Switch with 60-Degree Bending
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Solution Overview
Problem
Optical fiber technology faces challenges in bending angles due to total internal reflection, limiting flexibility in optical circuits requiring multiple signal direction changes, and existing photonic crystal switches lack compactness and high integration density.
Innovation Solution
A compact optical switch based on a two-dimensional photonic crystal with a 60-degree bending capability, utilizing a triangular lattice of holes in a magneto-optical material, where the electric permittivity is controlled by an external DC magnetic field to switch between on and off states, with linear defects forming waveguides and a resonant cavity that changes signal propagation direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If optical fiber technology uses total internal reflection for signal transmission, then signal transmission is achieved, but bending flexibility is limited
Solution Approach 1:
The patent replaces the mechanical/optical principle of total internal reflection with a photonic crystal-based electromagnetic wave guiding mechanism. The photonic crystal structure creates a photonic band gap that confines and guides electromagnetic waves through its periodic dielectric structure, eliminating the need for gradual bending radii required by total internal reflection and enabling sharp 60-degree bends while maintaining signal transmission reliability.
2Reliability
If photonic crystal switches are designed with conventional structures, then switching function is achieved, but device dimensions are large
Solution Approach 1:
The patent employs a two-dimensional photonic crystal structure with a triangular lattice configuration, utilizing periodic variation in dielectric constants in two dimensions to create a photonic band gap. This 2D approach enables compact device design with reduced dimensions compared to conventional 3D photonic crystal structures, while maintaining effective switching functionality through the formation of defect modes within the band gap.
3Adaptability or versatility
If optical circuits require multiple signal direction changes, then signal routing flexibility is improved, but optical fiber bending complexity increases
Solution Approach 1:
The patent segments the optical circuit into modular photonic crystal components, each capable of performing specific functions such as waveguiding, bending, and switching. The 60-degree bending capability is achieved through segmented photonic crystal structures with specific defect patterns, allowing multiple direction changes to be implemented as discrete, manageable units rather than continuous complex bends, thereby reducing overall device complexity while maintaining routing flexibility.
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 solution provides flexibility in optical circuit design with reduced dimensions, high bandwidth, low insertion losses in the on state, and high isolation in the off state, enabling increased integration density and simplified magnetization with a proportional magnetic field.
Implementation Method 1
a two-dimensional photonic crystal with a triangular lattice of holes made in a magneto-optical material whose electric permittivity depends on the intensity of an applied external DC magnetic field
Implementation Method 2
a periodic modulation of the electric permittivity or magnetic permeability of the different materials that constitute them. As a result, a range of forbidden frequencies, known as photonic band gap, is originated from the characteristic band diagram of these structures
Implementation Method 3
Some defects are inserted on the crystal, in a controlled manner, and they originate the waveguides and resonant cavity of the device
Data Source
AI summary
The present invention is based on a two-dimensional photonic crystal in which are inserted, in a controlled manner, defects that originate the waveguides and the resonant cavity that integrate the device. Its main function is to provide the control of the passage of an electromagnetic signal over a communications channel, blocking (state off) or allowing (state on) the passage of the signal. It also has the function of changing the propagation direction of an electromagnetic signal by an angle of 60 degrees, offering greater flexibility in the design of integrated optical systems. The operating principle of the device is associated with the excitation of dipole modes in the resonant cavity, which is based on a magneto-optical material. When the switch is under the influence of an external DC magnetic field H0, a rotating dipole mode excited in the cavity allows the passage of the input signal to the output (state on), whereas without the application of H0, a stationary dipole mode excited in the cavity, with the nodes aligned to the output waveguide, prevents the passage of the input signal to the output (state off).