Monolithic Diode Array Layout for Dense Independently Driven Beams
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Solution Overview
Problem
Existing monolithic edge-emitting semiconductor diode arrays for display applications, particularly in VR/AR, face challenges in achieving high frame refresh rates and small pixel sizes due to limitations in beam collimation and independent control of individual emitters, often requiring external optical components like lenses and mirrors to align closely spaced beams.
Innovation Solution
A monolithic edge-emitting semiconductor diode array chip with a conductive substrate, semiconductor layers, ridges forming waveguides, and trenches for electrical isolation, along with a photonic integrated circuit (PIC) to bring output beams closer together and enable independent control of each diode through separate anode and cathode contacts, reducing the need for external optical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If external optical components (lenses and mirrors) are used to align and manipulate output beams from individual emitters, then beam spacing and parallelism can be controlled, but device complexity and size increase
Solution Approach 1:
The patent integrates the beam manipulation function directly into the semiconductor chip by forming waveguides within the semiconductor layers themselves. The ridges extend between front and back chip facets, guiding light propagation and controlling beam spacing and parallelism without requiring external lenses or mirrors. This merging of functions eliminates the need for separate external optical components while maintaining precise beam control.
Solution Approach 2:
The patent introduces waveguides as intermediary structures formed within the semiconductor layers to transfer and manipulate light beams. These waveguides act as intermediaries between the light-emitting regions and the external environment, controlling beam propagation, spacing, and parallelism through the ridge structures embedded in the semiconductor material.
2Area of moving object
If individual emitters are made closely spaced to reduce pixel area, then pixel density increases, but independent control of each emitter becomes more difficult
Solution Approach 1:
The patent divides the semiconductor chip into multiple independently controllable emitters by forming separate light-emitting regions within the semiconductor layers. Each emitter can be individually addressed and controlled through its own waveguide structure, allowing independent modulation even when emitters are closely spaced. This segmentation enables high pixel density while maintaining ease of independent control.
Solution Approach 2:
The patent uses the vertical dimension by forming waveguides that extend through multiple layers of the semiconductor structure. The ridges penetrate through the semiconductor layers, providing a three-dimensional approach to emitter isolation and control. This allows closely spaced emitters in the lateral direction to remain independently controllable through their distinct vertical waveguide paths.
3Productivity
If fast modulation of diode emitters is implemented to achieve high frame refresh rates, then display performance improves, but device complexity increases
Solution Approach 1:
The patent enables each diode emitter to be independently and rapidly modulated through direct electrical control of the semiconductor structures. The waveguide-integrated design allows fast modulation of individual emitters without requiring complex external modulation systems, as the modulation can be applied directly to the semiconductor diodes through their electrical contacts.
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 allows for high-speed, independent control of each diode emitter, reducing beam spacing and eliminating the need for external optics, enhancing frame refresh rates and pixel density in VR/AR applications.
Implementation Method 1
The passive waveguides are formed in a photonic integrated circuit (PIC)... to bring the outputs from different edge-emitting LD sources or superluminescent diode (SLD) sources closer together
Implementation Method 2
each being configured to emit an output beam from the front chip facet when driven under forward bias
Data Source
Figure 1A~2C
Figure 3A~3B
Figure 4A~4B
AI summary
A monolithic edge-emitting semiconductor diode array chip (100) comprises a one-dimensional array (70) of diode emitters (50), such as laser diodes, superluminescent diodes or semiconductor optical amplifiers. Semiconductor layers are arranged on a conductive substrate (1) and include active region layers (14) arranged between upper and lower cladding layers (12, 16) and separation layers (4, 5) arranged between the conductive substrate (1) and the lower cladding layer (16). The diode emitters (50) are formed by respective ridges (9) that are separated by trenches (25) which are sufficiently deep to penetrate into the separation layers (4, 5). Each diode (50) has its own upper and lower contacts (22, 24) that allow each diode (50) to be independently drivable with a current source driver circuit connected to push a modulated push current through its associated diode and/or a current sink connected to extract a modulated pull current through its associated diode.