Grating-Based Optical Transmitter Vertical Light Coupling
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Solution Overview
Problem
Conventional methods for coupling light in photonic integrated circuits, such as edge coupling, are time-consuming and expensive, and do not efficiently redirect light for optimal coupling with external media.
Innovation Solution
An optical apparatus with a light source region, reflector regions, an interference region, and a grating region with specific periodicity and duty cycles, configured to redirect light perpendicular to its propagation direction, allowing efficient coupling of light into and out of photonic integrated circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If edge coupling is used to couple light in photonic integrated circuits, then light coupling is achieved, but the process is time-consuming and expensive
Solution Approach 1:
The patent transitions from conventional edge coupling (lateral direction) to grating-based coupling (vertical direction perpendicular to the substrate). This dimensional change allows light to be coupled through the top surface of the photonic integrated circuit rather than requiring edge preparation, thereby eliminating time-consuming packaging processes while maintaining effective light coupling
2Ease of manufacture
If conventional edge coupling is used, then light coupling is achieved, but packaging complexity is high
Solution Approach 1:
By coupling light vertically through the substrate surface rather than laterally through edges, the patent eliminates the need for complex edge preparation, alignment, and packaging procedures. The grating structure enables direct coupling through the top surface, significantly reducing packaging complexity
Solution Approach 2:
The grating structure is integrated directly into the photonic integrated circuit substrate, allowing the device to perform its own coupling function without requiring external packaging components or complex assembly procedures. The grating itself serves as the coupling interface
3Loss of energy
If light is coupled at an angle perpendicular to propagation direction, then back reflection is minimized, but coupling efficiency must be optimized
Solution Approach 1:
The patent modifies the grating parameters (period, depth, duty cycle) to optimize coupling efficiency for vertical light injection. By carefully selecting these parameters, the grating achieves high coupling efficiency while maintaining the perpendicular coupling angle that minimizes back reflection into the light source
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 reduces packaging costs and complexity by enabling efficient light coupling at an angle perpendicular to the propagation direction, minimizing back reflection and mode matching losses, and allowing for active tuning of the interference region for wavelength selection or absorption enhancement.
Implementation Method 1
a first reflector region and a second reflector region configured to reflect the generated light to form an interference light along a first direction
Implementation Method 2
the grating region is configured to emit at least a portion of the light along a second direction that is different from the first direction
Data Source
AI summary
A grating based optical transmitter includes a light source region coupled to an interference region, two reflective regions on both sides of the interference region, and one or several gratings interacting with the interference light wave in the interference region causing a vertical emission. Two electrodes are used to inject electrical carriers, and a third electrode can be added to modulate the electrical carrier density recombined in the light source region. Compared to conventional edge-emitting laser with two electrodes, the grating-based optical transmitter in this invention largely reduces the packaging cost and complexity due to the vertical emission, and largely enhances the modulation bandwidth due to the three-terminal configuration.