Here we proposed three adiabatically coupled waveguides (ACW), while the outer waveguides perform as a two-mode system analogous to ground- and excited- states and the middle waveguide is same as dark-state in a three-level-atomic system. Thanks to the dark-state, intermediate waveguide is based on plasmonic Indium thin oxide (ITO) as an active structure. Our simulation indicates a power consumption of 40 atto-joule with 50 dB modulation depth. In addition, our ACW plasmonic modulator provides high-speed operation as high as 5.4 THz and insertion loss as low as 0.45 dB. The proposed device is crucial for futuristic of optical short-reach interconnects.
We propose adiabatic elimination (AE) to suppress the cross-talk in ultra-dense optical waveguides with sub-wavelength spacing. AE in atomic system is caused by a strong coupling nearby levels and a large detuning between them. Analogous to a three-level atomic system, in a set of three AE waveguides the outer waveguides function as an effective two-mode system like ground- and excited- states and the middle waveguide is same as dark state. While decomposition of three level system to two plus one has been reported previously, thanks to the “critical-point” three waveguides could be fully decomposed into three separate waveguides. Here we calculated the power profile using combination of three-dimensional (3D) finite difference time domain (FDTD) and 3D eigen-mode expansion method. At the input waveguide, initial amplitude of super-eigen-modes are obtained with 3D FDTD and the optical power in the three arms is then simulated with the overlap integral of the propagating super-eigen-modes with the fundamental transverse-electric (TE) of the isolated three waveguides. In the conventional coupled waveguides, sufficient inversion length at the telecommunication wavelength (1530 nm to 1565 nm) requires lambda spacing. Thanks to the critical point in our proposed waveguide, ultra-dense packaging with spacing as low as lambda/6, inversion length of several millimeters and cross-talk as low as 1 dB is obtained. Our preliminary experimental results are in good-agreement with the design. This concept can be extended to numerous number of optical waveguides. This AE waveguides will pave the way to ultra-dense multiplexing system as well as optical short-reach interconnects.
A photonic microwave sensor based on electro-optic (EO) polymer infiltrated silicon subwavelength grating (SWG) waveguide and bowtie antenna is designed and experimentally demonstrated. The microwave sensor receives wireless microwave signals via the bowtie antenna. The electrical field between the extension bars of the bowtie antenna modulates the light guided in the SWG based Mach–Zehnder interferometer (MZI). Thus, microwave signals can be detected by measuring the intensity variation of light from the MZI output. The EO polymer infiltrated SWG does not require ion implantation and has low optical propagation loss. Furthermore, compared to slotted silicon waveguides, the EO polymer poling efficiency on SWG structure can be greatly increased due to wider poling separations and thus the increased breakdown voltage. In order to achieve strong microwave field enhancement, the impedance of the bowtie antennas is tailored. The optimized bowtie antennas operate at 15 GHz and provide >1000X field enhancement while only occupy an area of 7.6 mm X 0.3 mm. Leveraging the folded SWG waveguide, high EO coefficient polymer, and large field enhancement from bowtie antenna, an ultra-sensitive and compact microwave photonic sensor has been demonstrated.
A complete inkjet printed 3D structure containing broadband antennas in a phased array configuration along with a fixed time delay phase shifter is demonstrated via simulation to allow for a Frequency Scanning Array. Continuous steering as a function of frequency and the necessary broadband antenna structures are explored, which allows for free space wireless communications and remote sensing applications. Finally, the capability of a single antenna to receive from multiple angles simultaneously is described.
Here a photonic waveguide on Al2O3/SiO2 platform is proposed to cover the 240~320 nm wavelength-range, which is of paramount significance in protein and nuclei acid quantification. Our optical waveguide increases path-length and overlap integration for light-matter interaction with proteins. The proposed system detects one order less proteins concentration as low as 12.5 μg/ml compared with NanoDropTM that detects <125 μg/ml. Also, a linear absorbance change up to protein concentration of 7500 μg/ml is experimentally attained which is based on the Beer-Lambert-law.
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