Segmented VCSEL Structure for Defect-Tolerant High Output
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Solution Overview
Problem
Large VCSEL devices are prone to failure due to single pixel defects, which can cause total device failure, and existing technologies struggle to maintain reliability and separation of optical modes in large area arrays, leading to inefficiencies and potential damage from local heating.
Innovation Solution
A VCSEL device with a guiding structure that separates optical modes and reduces intensity outside light emitting areas, using oxidized regions within the distributed Bragg reflector to confine current and prevent energy transfer between neighboring regions, thereby isolating defects and maintaining device functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large VCSEL devices are used to increase output power, then power output is improved, but reliability deteriorates due to single pixel defects causing total device failure
Solution Approach 1:
The active layer is divided into multiple independent light emitting areas (first, second, third areas) that are spatially separated by guiding structures. Each area can emit light independently through its own optical mode, allowing the device to maintain high total output power while ensuring that a defect in one area does not cause complete device failure - the other areas continue to function.
2Power
If large VCSEL devices are used to increase output power, then power output is improved, but intensity concentration and local heating worsen outside light emitting areas
Solution Approach 1:
The guiding structure is designed to create localized optical confinement with different properties in different regions. Within each light emitting area, the structure supports resonant modes that concentrate intensity for efficient light emission. Between the light emitting areas, the guiding structure creates regions where optical modes are suppressed, preventing intensity concentration and subsequent local heating in non-emitting regions.
3Device complexity
If optical modes are not separated in large area arrays, then device complexity is reduced, but energy transfer between neighboring regions causes inefficiencies and potential damage
Solution Approach 1:
The guiding structure spatially segments the optical modes into distinct regions corresponding to each light emitting area. This segmentation prevents cross-talk and energy transfer between neighboring regions by creating optical isolation through the guiding structure's design, which confines each mode to its designated light emitting area while maintaining overall device structural simplicity.
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 enhances the reliability and stability of VCSEL devices by preventing energy transfer between light emitting areas, localizing defects, and maintaining high output power, making them suitable for harsh applications like automotive use.
Implementation Method 1
The guiding structure is arranged to reduce an intensity of at least one optical mode contributing to at least one of the first or second relative intensity maxima outside the at least the first or the second light emitting area
Implementation Method 2
a series of concentric rings is formed in the blocking layer surrounding the resonant cavity so as to provide a Bragg structure which reflects light from the cavity with a phase characteristic that supports the preselected transverse resonant mode
Implementation Method 3
an active layer, a distributed heterojunction bipolar phototransistor... wherein the distributed heterojunction bipolar phototransistor is arranged such that there is an optical coupling between the active layer and the distributed heterojunction bipolar phototransistor
Data Source
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AI summary
The invention a Vertical Cavity Surface Emitting Laser device (100). The Vertical Cavity Surface Emitting Laser device (100) comprises a first electrical contact (105), a substrate (110), a second electrical contact (135) and an optical resonator. The optical resonator is arranged on a first side of the substrate (110). The optical resonator comprises a first reflecting structure comprising a first distributed Bragg reflector (115), a second reflecting structure comprising a second distributed Bragg reflector (130), an active layer (120) arranged between the first reflecting structure and the second reflecting structure and a guiding structure (132). The guiding structure (132) is arranged within a layer stack of the first distributed Bragg reflector (115) or the second distributed Bragg reflector (130). The guiding structure (132) configured to provide a lateral variation of a reflectivity of the first reflecting structure or the second reflecting structure parallel to the active layer (120), wherein the guiding structure (132) is configured to define a first relative intensity maximum of an intensity distribution within the active layer (120) at a first lateral position of the optical resonator such that a first light emitting area (124) is provided, and at least a second relative intensity maximum of the intensity distribution within the active layer (120) at a second lateral position of the optical resonator such that second light emitting area (124) is provided, wherein the guiding structure (132) is further configured to reduce an intensity of the intensity distribution in between the at least two light-emitting areas (124) during operation of the Vertical Cavity Surface Emitting Laser device (100), wherein the guiding structure (132) comprises oxidized regions within at least one layer of the first distributed Bragg reflector (115) or the second distributed Bragg reflector (130), wherein the oxidized region are arranged to reduce the intensity in between the light-emitting areas (124). The invention further describes the optical sensor (300) comprising such a Vertical Cavity Surface Emitting Laser device (100), a mobile communication device (380) comprising such an optical sensor (300) and a method of fabricating the Vertical Cavity Surface Emitting Laser device (100).