Photodetectors with controllable resonant enhancement
Resonant cavity photodetector structures which integrate photodetection and filtering capabilities is described. A resonant cavity photodetector structure generally can comprise a region including a resonator, and an absorption region that can be integrated into a cavity of the resonator. The resonator can perform filtering that is suitable for high-bandwidth optical communications, such as Dense Wavelength Multiplexing (DWDM). In some cases, the resonator is a microring resonator. An absorption region can include a photodiode which performs optical energy detection acting as a photodetector, such as an avalanche photodiode (APD) wherein the photodiode. A coupling distance between the resonator region and the absorption region can be controlled, which allows control of a coupling strength between an optical mode of the resonator and the absorption region such that a quality factor (Q-factor) can be tuned. Thus, by adjusting the Q-factor, the resonant cavity photodetector structure can be tuned to achieve a desirable performance.
1. A resonant cavity photodetector structure device having photodetection and filtering capabilities, comprising:
a resonator region comprising a resonator photonic element, wherein the resonator photonic element performs resonance wavelength-based filtering to provide the filtering capabilities of the resonator photodetector device, wherein the resonator photonic element comprises a resonant cavity, and wherein the resonator photonic element is a microring resonator comprising a ring waveguide evanescently coupled to a bus waveguide;
an absorption region adjacent to the resonator region and comprising photodiode photonic elements, wherein the photodiode photonic elements perform optical energy detection to provide the photodetection capabilities, wherein the photodiode photonic elements comprise an avalanche photodiode (APD), wherein the absorption region comprising the APD is positioned within the cavity of the resonator photonic element within an area bordered by a diameter of the ring waveguide; and
a coupling distance between the resonator region and the absorption region, wherein the coupling distance is selectively adjusted to control a coupling strength between an optical mode associated with the resonator region and the absorption region and correspondingly control a quality factor (Q-factor) of the filtering capabilities.
2. The device of claim 1 , wherein the absorption region comprising the APD is positioned within the cavity of the resonator photonic element.
3. The device of claim 1 , wherein the coupling distance being selectively adjusted to increase a physical separation between an edge of the ring waveguide and the absorption region corresponds to lowering the coupling strength between an optical mode and the absorption region.
4. The device of claim 1 , wherein the coupling distance is selectively adjusted to control the Q-factor such that a channel spacing between 50 GHz and 200 GHz is supported in a dense wavelength division multiplexing (DWDM) system.
5. The device of claim 1 , wherein the APD comprises a silicon geranium (SiGe) APD.
6. A resonant cavity photodetector structure device having photodetection and filtering capabilities, comprising:
a resonator region comprising a resonator photonic element wherein the resonator photonic element performs resonance wavelength-based filtering to provide the filtering capabilities of the resonator photodetector device;
an absorption region adjacent to the resonator region and comprising photodiode photonic elements, wherein the photodiode photonic elements perform optical enemy detection to provide the photodetection capabilities, wherein the photodiode photonic elements comprise an avalanche photodiode (APD), wherein the APD is a separate-absorption-charge-and-multiplication (SACM) APD and a separate section of the SACM APD is positioned on a section of a ring waveguide; and
a coupling distance between the resonator region and the absorption region, wherein the coupling distance is selectively adjusted to control a coupling strength between an optical mode associated with the resonator region and the absorption region and correspondingly control a quality factor (Q-factor) of the filtering capabilities.
7. The device of claim 6 , wherein a physical size and an absorption layer thickness of the SACM APD are reduced such that a responsivity and a response speed of the device are increased.
8. A resonator photodetector device having photodetection and filtering capabilities, comprising:
a resonator providing the filtering capabilities of the resonator photodetector device, wherein the resonator is a microring resonator comprising a ring waveguide evanescently coupled to a bus waveguide; and
a photodetector positioned on a portion of the resonator and providing the photodetection capabilities of the photonic resonator device, wherein a photodetector size associated with the photodetector is selectively adjusted to be smaller than a resonator size associated with the resonator and reduce the overall size of the resonator photodetector device and correspondingly control a carrier transit time associated with a speed of the resonator photodetector device, and wherein the photodetector comprises an intrinsic silicon layer that is positioned on top of a portion of the ring waveguide.
9. The device of claim 8 , wherein the photodetector size is selectively adjusted to provide a capacitance that further controls the speed of the resonator photodetector device.
10. A resonant cavity photodetector structure device having photodetection and filtering capabilities, comprising:
a resonator region comprising a resonator photonic element, wherein the resonator photonic elements perform resonance wavelength-based filtering to provide the filtering capabilities of the resonator photodetector device, wherein the resonator photonic element comprises a microring resonator further comprising a ring waveguide evanescently coupled to a bus waveguide;
an absorption region adjacent to the resonator region and comprising an avalanche photodiode (APD) performing the photodetection capabilities, wherein the absorption region comprising the APD is positioned outside of an area bordered by a diameter of the ring waveguide; and
a coupling distance between the resonator region and the absorption region, wherein the coupling distance is selectively adjusted to control a coupling strength between an optical mode associated with the resonator region and the absorption region and correspondingly control a quality factor (Q-factor) of the filtering capabilities.