Tunable Reflectors Using Coupled Fabry-Perot Cavities

The patent changes the fundamental operating parameters from grating-based diffraction to resonant cavity-based interference. By using Fabry-Perot resonant cavities with carefully controlled lengths and refractive indices, the system achieves wavelength selection through resonance conditions rather than diffraction, enabling compact integration while maintaining precise wavelength control capability

The patent implements nested resonant cavities where one cavity is positioned within or alongside another cavity structure. This nesting approach allows multiple wavelength selection functions to be integrated in a compact footprint, with the inner cavity providing fine wavelength tuning and the outer cavity providing broader wavelength selection, thereby achieving precise wavelength control in a small device volume

The patent transitions from complex grating fabrication to simpler resonant cavity fabrication by changing the underlying physical principle. The resonant cavities can be formed using standard semiconductor processing techniques such as selective epitaxial growth and etching, which are more成熟 and easier to control than the precise patterning required for binary superimposed gratings, thereby improving ease of manufacture while maintaining wavelength control precision

The patent divides the wavelength control function into separate, modular resonant cavity components. Each cavity can be independently fabricated and then integrated, allowing for modular manufacturing and testing. This segmentation simplifies the overall fabrication process compared to creating a single complex grating structure, as each cavity segment can be optimized and fabricated using standard process steps

The patent implements dynamically tunable resonant cavities where the cavity length or refractive index can be adjusted after fabrication using techniques such as electro-optic or thermo-optic effects. This dynamic capability allows the system to achieve high reflectance at specific wavelengths only when needed, reducing average power consumption compared to static high-reflectance structures that continuously consume power to maintain their reflective state

The patent utilizes changes in refractive index or cavity dimensions through external control signals to tune the resonant wavelengths. By changing these parameters dynamically, the system achieves high wavelength selectivity only during active tuning periods, rather than requiring continuous high power input to maintain fixed high reflectance, thereby reducing overall power consumption while maintaining selectivity when required