Electrically Pumped Parametric Optical Source on Chip
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Solution Overview
Problem
Current electrically pumped on-chip optical parametric oscillators face challenges in achieving phase matching between different beams, limiting tunability and power levels, due to narrow phase matching bands and high series resistance, which hampers their effectiveness in producing coherent infrared radiation.
Innovation Solution
The use of quantum dots as the gain medium in a semiconductor laser diode with a narrow ribbon structure and optimized optical confinement layers allows for improved phase matching, increased power, and tunability, reducing series resistance through selective doping and dielectric mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional semiconductor laser structures are used for parametric generation, then device compactness and electrical pumping are achieved, but phase matching between different beams is difficult to obtain
Solution Approach 1:
The patent changes the physical parameters of the semiconductor structure by introducing quantum dots with specific size distributions and compositions (e.g., InGaAsP quantum dots in GaAs matrix) to achieve phase matching. By adjusting quantum dot dimensions and material composition, the refractive index and non-linear optical coefficients are optimized to satisfy phase matching conditions for parametric generation at different wavelengths.
Solution Approach 2:
The patent employs composite semiconductor structures combining different materials (GaAs, InGaAsP, AlGaAs) with distinct optical properties. The quantum dots are embedded in a semiconductor matrix, creating a composite structure that enables simultaneous optical confinement and phase matching. This composite approach allows independent optimization of gain medium and optical waveguide properties.
2Measurement precision
If narrow phase matching bands are used to achieve wavelength selectivity, then spectral precision is improved, but power levels and tunability are limited
Solution Approach 1:
The patent introduces dynamic tuning capabilities by making the phase matching condition adjustable. Quantum dot composition and size can be varied to tune the parametric generation wavelength. Additionally, temperature tuning and pump wavelength tuning enable dynamic adjustment of the signal and idler wavelengths while maintaining phase matching, thus achieving both wavelength selectivity and broad tunability.
Solution Approach 2:
By changing the pump wavelength and temperature parameters, the patent achieves broad wavelength tunability. The quantum dot structure allows continuous tuning of the parametric generation wavelengths by adjusting the pump wavelength, while the non-degenerate configuration enables independent tuning of signal and idler wavelengths, overcoming the narrow bandwidth limitation of degenerate OPOs.
3Ease of operation
If conventional optical confinement structures are used, then optical confinement is achieved, but series resistance remains high
Solution Approach 1:
The patent segments the contact structure into multiple regions with different doping types (n-type and p-type contacts at different locations). This segmentation allows separate current injection paths and reduces the overall series resistance by optimizing the electrical contact configuration independent of the optical confinement structure.
Solution Approach 2:
The patent introduces intermediate doped layers and contact structures that serve as electrical mediators between the external circuit and the active region. These intermediary structures provide low-resistance current paths while maintaining the optical confinement properties of the quantum dot active region, thus decoupling electrical and optical design constraints.
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 enables a compact, tunable, and high-power optical parametric oscillator capable of emitting coherent radiation in the 1-3 μm wavelength range, overcoming previous limitations in phase matching and power output.
Implementation Method 1
the active layer comprising at least one plane of quantum dots able to emit a pump wave at a pump wavelength
Implementation Method 2
a first optical confinement layer extending along a reference plane Oxy and forming a distributed Bragg reflector for a pump wave at a pump wavelength
Implementation Method 3
the part of the active layer comprising the plane of quantum dots; the second optical confinement layer; said strip allowing the emission, by parametric conversion from the pump wave, of two waves, called respectively 'signal wave' and 'complementary wave'
Implementation Method 4
the second width being less than 10 μm, the active layer comprising at least one plane of quantum dots
Data Source
Figure 1a~1c
Figure 2
Figure 3a~3b
AI summary
The invention essentially relates to a tunable laser source (100, 100') comprising: - a first confinement layer (112, 212) forming a Bragg mirror for a pump wave; - an active layer (113, 213) made of a nonlinear semiconductor material, the refractive index of the active layer being greater than the refractive index of the first confinement layer; - a second confinement layer (115, 215), the refractive index of the second confinement layer being less than the refractive index of the active layer; - a base (104, 204) having a first width; - a ribbon (105, 205) having a second width less than said first width. The second width is less than 10 µm; the active layer comprises at least one plane of quantum dots capable of emitting a pump wave, and the ribbon comprises at least the portion of the active layer including the plane of quantum dots and the second confinement layer.