Self-Injection-Locked Soliton Microresonator Pulse Source on Chip
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Solution Overview
Problem
Conventional techniques for generating frequency combs with optical microresonators rely on external bulk laser modules for coherence, frequency agility, and power, making full photonic integration challenging due to high soliton formation thresholds and frequency agility requirements, especially with silicon-based lasers.
Innovation Solution
A compact light pulse source integrating a continuous wave (cw) laser device and an optical microresonator on a common chip substrate, where the cw laser device is a chip-based semiconductor laser providing direct electrical pumping, and the optical microresonator has third-order nonlinearity and anomalous dispersion, enabling self-injection locking and soliton state tuning via driving current and temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external bulk laser modules are used for generating frequency combs with optical microresonators, then coherence, frequency agility, and power requirements are met, but device size, complexity, and integration difficulty increase
Solution Approach 1:
The patent combines the laser source and microresonator onto a single photonic integrated circuit chip, merging previously separate bulk components into an integrated device. This reductionist approach maintains the necessary optical functions while eliminating the complexity of external bulk laser modules and their associated alignment and stabilization systems.
Solution Approach 2:
The patent introduces a photonic integrated circuit as an intermediary platform that mediates between the laser source and microresonator. This intermediary enables coherent coupling and frequency control while providing a standardized interface that simplifies integration and reduces the need for complex external alignment systems.
2Reliability
If high soliton formation thresholds are used in optical microresonators, then soliton state is achieved, but power consumption and device complexity increase
Solution Approach 1:
The patent modifies key parameters of the microresonator system, including quality factor (Q-factor) enhancement through low-loss waveguide designs and dispersion engineering. By changing these parameters, the soliton formation threshold is reduced to levels compatible with integrated laser sources, thereby lowering power consumption while maintaining soliton stability.
Solution Approach 2:
The patent implements preliminary dispersion management and mode matching in the photonic integrated circuit design to pre-condition the optical field for efficient soliton formation. This preliminary action reduces the pump power required to reach the soliton threshold by ensuring optimal coupling conditions before the light enters the microresonator.
3Adaptability or versatility
If frequency agility requirements are increased for soliton initiation, then soliton microcomb generation is enabled, but device complexity and control difficulty increase
Solution Approach 1:
The patent implements dynamic frequency tuning capabilities through thermally actuated phase shifters and carrier-injected resonators integrated into the photonic circuit. These dynamic elements enable real-time frequency adjustment of the laser source to track microresonator resonances, providing the necessary frequency agility for soliton initiation without requiring complex external tuning mechanisms.
Solution Approach 2:
The patent incorporates feedback control systems that monitor the microresonator transmission spectrum and automatically adjust the laser frequency to maintain optimal coupling conditions. This feedback mechanism simplifies the control of frequency agility by using closed-loop stabilization rather than complex open-loop tuning procedures.
4Device complexity
If chip-based semiconductor lasers are used instead of bulk lasers, then device size and integration are improved, but output power and coherence may be insufficient
Solution Approach 1:
The patent employs a nested structure where the microresonator acts as a nested cavity within the photonic integrated circuit, which itself is nested on the semiconductor substrate. This nested architecture allows the chip-based laser to efficiently couple into the high-Q microresonator, building up sufficient optical power through resonant enhancement despite the low initial laser output power.
Solution Approach 2:
The patent uses composite material structures in the photonic integrated circuit, including hybrid semiconductor-dielectric waveguides and multi-layer resonator designs. These composite structures enable efficient light confinement and low-loss propagation, maximizing the utilization of the chip laser's output power while maintaining coherence through material engineering.
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 approach facilitates electrically-driven, current-initiated soliton microcombs with reduced size, cost, and weight, enabling scalable manufacturing for high-volume applications like laser ranging and optical interconnects, while maintaining high-Q microresonator quality and sufficient output power for soliton initiation.
Implementation Method 1
The optical microresonator is made of a resonator material, which has a third order (Kerr) nonlinearity and an anomalous resonator dispersion
Implementation Method 2
The optical microresonator is made of a resonator material, which has a third order (Kerr) nonlinearity and an anomalous resonator dispersion
Implementation Method 3
the cw laser device is a chip based semiconductor laser providing direct electrical pumping
Data Source
Figure 1~2B
Figure 3~5
Figure 6a~6f
AI summary
A light pulse source (100), being adapted for generating repetitive optical pulses (1), comprises a continuous wave cw laser device (10) being arranged for providing cw laser light (2), an optical waveguide (20) being optically coupled with the cw laser device (10),an optical microresonator (30) being made of a resonator material, which has a third order Kerr nonlinearity and an anomalous resonator dispersion, wherein the cw laser device (10) and the optical microresonator (30) are arranged on a common chip substrate device (40) for coupling the cw laser light (2) via the optical waveguide (20) into the optical microresonator (30), which, at a predetermined output frequency of the cw laser device (10), is capable of including a light field in a soliton state, so that soliton shaped pulses can be coupled out of the optical microresonator (30) for providing the repetitive optical pulses (1), and a tuning device (50) being arranged for adjusting the output frequency of the cw laser device (10), wherein the cw laser device (10) comprises a chip based semiconductor laser (11), at least one of the optical microresonator (30) and the optical waveguide (20) is adapted for reflecting an optical feedback portion (3) of light back to the semiconductor laser (11), which is capable of providing self injection locking relative to a resonance frequency of the optical microresonator (30) by the effect of the optical feedback portion (3), and the tuning device (50) is arranged for tuning at least one of a driving current and a temperature of the semiconductor laser (11) such that the optical microresonator (30) is capable of providing the soliton state. Furthermore, a light pulse generation method is described.