III-V Membrane Broadband Light Source for Silicon Photonic Chips
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Solution Overview
Problem
Current photonic integrated circuits face inefficiencies in producing a broadband light source due to silicon's indirect bandgap, leading to low power output and complex, costly fabrication processes, especially in applications like spectroscopic biosensing, where a reliable and efficient on-chip broadband source is crucial.
Innovation Solution
A photonics integrated circuit with an on-chip broadband radiation source is achieved by using a III-V membrane with a taper or grating coupling means, optically pumped to induce broadband radiation, which is efficiently coupled back into the optical waveguide, minimizing power consumption and fabrication complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon is used as the light emitting material in photonic integrated circuits, then the circuit can be manufactured using established microelectronics technologies, but the light emission efficiency is low due to silicon's indirect bandgap
Solution Approach 1:
The patent uses a composite structure combining silicon waveguide with a III-V membrane (containing quantum well layers). The silicon provides the waveguide structure and optical confinement, while the III-V material provides efficient light emission. This composite approach leverages the advantages of both materials: silicon'sæç manufacturing and optical guiding properties, and III-V's direct bandgap light emission efficiency.
Solution Approach 2:
The light emitting function is segmented from the silicon waveguide structure. Instead of attempting to make silicon emit light directly, the patent separates the guiding function (silicon) from the emission function (III-V membrane with quantum wells), allowing each component to be optimized independently.
2Loss of energy
If heterogeneous integration of III-V materials is used to improve light emission efficiency, then the light emission capability is enhanced, but the design and fabrication complexity increases significantly
Solution Approach 1:
The patent employs a thin III-V membrane structure that can be integrated onto the silicon waveguide. This thin-film approach reduces the complexity of heterogeneous integration compared to bulk material bonding, while still providing sufficient active volume for efficient light emission through the quantum well layers.
Solution Approach 2:
The III-V membrane with quantum well layers is nested within or onto the silicon waveguide structure. The membrane contains multiple functional layers (quantum wells, barriers, cladding) that are nested hierarchically, allowing complex functionality to be achieved through layered integration rather than complex lateral structures.
3Ease of manufacture
If electrically pumped LEDs are used to generate broadband light, then the light source can be integrated on-chip, but the power output is low and the coupling efficiency to the waveguide is poor
Solution Approach 1:
The patent employs an adiabatic taper structure that dynamically transforms the optical mode from the waveguide to the free-space mode above the III-V membrane. The taper's gradually varying geometry allows the optical field to adapt continuously, maximizing coupling efficiency and power extraction from the LED into the waveguide.
Solution Approach 2:
The patent changes the geometric parameters of the waveguide structure along its length (creating a taper) to optimize light coupling. The taper ratio and length are specifically designed to match the mode fields between the waveguide and the LED emission region, transforming optical parameters to maximize power transfer.
4Power
If laser coupling is used to provide a light source for the optical waveguide, then the power output is sufficient, but the optical alignment requirements are very exact and packaging costs increase
Solution Approach 1:
The patent merges the light source (III-V LED) and the waveguide into a single integrated structure. The LED is directly coupled to the waveguide through the taper, eliminating the need for separate laser sources and complex alignment mechanisms. This integration maintains sufficient power output while dramatically simplifying packaging and alignment requirements.
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 provides a highly efficient, low-power consumption broadband light source with improved coupling efficiency, suitable for applications like spectroscopic biosensing and microscopy, by leveraging the high refractive index contrast and absorption capabilities of III-V materials integrated with silicon-on-insulator waveguides.
Implementation Method 1
the III-V membrane has an absorption capability for absorbing the optical pump signal transferred up to the III-V membrane so as to pump the LED structure thus inducing broadband radiation at a wavelength longer than the wavelength of the optical pump signal
Implementation Method 2
the coupling means is a taper or a grating, and the III-V membrane has an absorption capability for absorbing the optical pump signal transferred up to the III-V membrane
Implementation Method 3
The III-V membrane furthermore is adapted for transferring back the broadband emitted light to the optical waveguide mentioned above
Data Source
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AI summary
The present invention relates to an on-chip broadband radiation source, and methods for its manufacture. The photonics IC comprises an optical waveguide such as a semiconductor waveguide, a thin III-V material membrane with absorption capability for absorbing an optical pump signal induced in the waveguide. The III-V membrane comprises a LED implemented therein. The photonics IC also comprises a coupling means between the waveguide and the membrane. The device provides a broadband radiation source at a wavelength longer than the wavelength of the transferred radiation. The broadband signal can then be coupled out through the waveguide and used in the chip.