Trench-Patterned Mode-Locked Laser for Equidistant Resonance Modes
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Solution Overview
Problem
Current mode-locked lasers integrated on silicon photonic chips have limitations, such as single natural mode of resonance and inability to emit phase-synchronized multimode laser pulses, which restricts high data rates and precision in applications like telecommunications and metrology.
Innovation Solution
A mode-locked laser design featuring a resonant cavity with a rib structure and waveguide on a silicon substrate, incorporating a saturable absorbent layer and trenches with varying parameters following a symmetric polynomial law, allowing for multiple equidistant resonance modes and efficient phase-synchronized multimode pulse emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional laser source with a single natural mode of resonance is used, then the structure is simple, but it cannot emit phase-synchronized multimode laser pulses
Solution Approach 1:
The resonant cavity is segmented into multiple sections by introducing periodic trenches at specific positions. These trenches divide the cavity into distinct regions that support multiple equidistant resonance modes, enabling multimode pulse emission while maintaining a structured and manageable design
Solution Approach 2:
The trenches are positioned at specific locations within the cavity where the optical field intensity has local maxima. This local placement strategy optimizes the coupling between the trenches and the optical modes, enhancing the ability to sustain multiple resonance modes with appropriate quality factors
2Adaptability or versatility
If the cavity length is increased to accommodate multiple equidistant resonance modes, then multimode emission is enabled, but the device size increases
Solution Approach 1:
The periodic trenches modify the optical path length and effective refractive index within the cavity. By changing these optical parameters through the trenches' geometry and positioning, multiple resonance modes are achieved without proportionally increasing the physical cavity length, thus maintaining a compact device size
3Adaptability or versatility
If a saturable absorbent layer is added to enable mode-locking, then phase-synchronized pulses are achieved, but energy consumption increases
Solution Approach 1:
The saturable absorbent layer operates passively by exploiting the intensity-dependent absorption特性 of the material. High-intensity pulses saturate the absorption and experience low loss, while low-intensity continuous wave experiences high absorption. This self-regulating mechanism enables mode-locking without requiring external energy input or active control
4Manufacturing precision
If trenches with varying parameters are introduced to achieve equidistant modes, then resonance mode distribution is improved, but manufacturing precision requirements increase
Solution Approach 1:
The trench positions and dimensions are pre-calculated based on the desired equidistant resonance mode spacing before fabrication. This preliminary design stage allows for optimization of the trench parameters to achieve the target mode distribution, simplifying the actual manufacturing process by providing clear fabrication guidelines
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 design enables the emission of phase-synchronized multimode laser pulses with high precision and low energy consumption, suitable for high data rate applications and metrology, while being easily integrable on silicon structures with reduced bulk and power consumption.
Implementation Method 1
the rib also comprises an absorbent layer extending below the lower layer along the stacking direction, the absorbent layer comprising a saturable absorbent material at at least one resonant frequency of the cavity
Implementation Method 2
the cavity being able to accommodate a plurality of frequency equidistant resonance modes
Data Source
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AI summary
Mode-locked laser (10) comprising: - a substrate (12), - a rib (14) that extends over the substrate, - a resonant cavity (15) defined in the substrate plumb with the rib, and - a waveguide (16) defined in the substrate. The rib comprises a lower layer (C2), a plurality of intermediate layers (C3 to CN-1) and an upper layer (CN). The cavity comprises a plurality of trenches (36) produced in at least one of the faces (44). Each trench has parameters, comprising: - a width, - a thickness, - a depth, and - a dimension of a spacing separating each trench. At least one parameter varies, in the direction of extent (X), according to a symmetric polynomial law of variation of order higher than or equal to four.