- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Design of a C-band polarization rotator-splitter based on a mode-evolution structure and an asymmetric directional coupler
摘要： A C-band polarization rotator-splitter based on a mode-evolution structure and an asymmetric directional coupler is proposed. The mode-evolution structure is designed in a bi-level taper through which the TM0 mode can evolve into the TE1 mode. Then the TE1 mode is coupled to the TE0 mode at the cross port using the asymmetric directional coupler. The input TE0 mode propagates along the waveguide without mode conversion and output at the through port. From the experimental results, the extinction ratio is lower than 30 dB and the excess loss is less than 1 dB for input TE0 mode at the whole C-band. For input TM0 mode, the ER and the EL are, respectively, lower than ?10 and 1.5 dB.
关键词： silicon photonics,integrated optic devices,polarization rotator splitters
更新于2025-09-23 15:23:52
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While rotating while cloaking
摘要： Invisible optical and thermal cloaking have been explored as the typical demonstrations of the transformation optics and thermotics theory. However, the existing cloaks are realized by only one-coordinate transformation, and the cloaking layout, i.e. the form of electromagnetic wave/heat passing around the invisible region, is single for a long time. Here, we propose a new rotated thermal cloak which can unify the conventional cloaking and rotating together, and realize the while-rotating–while-cloaking effect. The required anisotropic thermal conductivity tensor is deduced from the new geometric mapping. Though rotated, the heat ?ux can be tuned around the central invisible region perfectly by the proposed rotated thermal cloak. The underlying physics is explored by comprehensive analysis of the distribution of the thermal conductivity tensor, which is further compared with those of the conventional cloak and rotator. The experimental feasibility is also discussed by validating the practical while-rotating–while-cloaking effect through a proof-of-concept design. The proposed rotated thermal cloak is expected to extend the possibility of cloaking scheme, and open avenues for the multiple coordinate transformation in counterpart physical ?elds, like optics, electrics, acoustics, magnetics, mechanics, etc.
关键词： Coordinate transformation,Thermal rotator,Thermal cloak,Transformation thermotics
更新于2025-09-23 15:22:29
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - A Way to Realize a Multi-Frequency Polarization Plane Rotator
摘要： In this paper, we propose a simple design of a planar-chiral screen based polarization plane rotator that enables a polarization conversion at two assigned frequency bands simultaneously. The rotator is composed of a pair of conjugated double periodic perforated screens separated by a short distance. Two groups of four rectangular slots are cut along a perimeter of the screen periodical cell. Polarization rotation frequencies are controlled by choosing appropriated dimensions and placements of the slots’ groups. At the same time, we report that even a rotator with equal slots belonging to different (outer or internal) quadruples enables a dual-frequency operation as well.
关键词： optical activity,frequency-selective surface,rotator,polarization conversion
更新于2025-09-23 15:21:21
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Ultra-broadband mid-infrared Ge-on-Si waveguide polarization rotator
摘要： The design, modeling, micro-fabrication, and characterization of an ultra-broadband Ge-on-Si waveguide polarization rotator are presented. The polarization rotator is based on the mode evolution approach where adiabatic symmetric and anti-symmetric tapers are utilized to convert from the fundamental transverse magnetic to electric mode. The device is shown to be extremely fabrication tolerant and simple to fabricate. The fabricated devices demonstrate a polarization extinction ratio of ≥15 dB over a 2 μm bandwidth (9–11 μm wavelength) with an average insertion loss of <1 dB, which is an order of magnitude improvement compared to previously demonstrated devices. This device will provide polarization flexibility when integrating quantum cascade lasers on-chip for mid-infrared waveguide molecular spectroscopy.
关键词： mid-infrared,Ge-on-Si,polarization rotator,waveguide,quantum cascade lasers
更新于2025-09-23 15:19:57
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Broadband Polarization Splitter-Rotator and the Application in WDM Receiver
摘要： Polarization sensitivity is a severe problem in photonic integration devices and chips based on the high-index contrast Si/SiO2 system. In this paper, a broadband silicon polarization splitter-rotator (PSR) comprised of a bi-level taper and a counter-tapered coupler is proposed with a large fabrication tolerance. The measured insertion loss is lower than 0.7 dB/0.73 dB for the wavelength range from 1470 to 1580 nm with a crosstalk lower than ?12.1 dB/?14.7 dB for TE and TM polarization input, respectively. By integrating the PSR with silicon arrayed waveguide gratings and germanium photodetectors (PDs) on a single chip, a polarization-insensitive wavelength-division-multiplexing (WDM) receiver is demonstrated with a polarization-dependent loss as low as 1.21 dB. High-speed operations are also achieved with clear eyes at 10 Gb/s.
关键词： Polarization splitter-rotator,silicon photonics,integrated photonic chips
更新于2025-09-19 17:15:36
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Radiation from junctions between two-dimensional plasmonic waveguides
摘要： We propose a digitally controlled injection-locked RF oscillator with an auxiliary loop as an alternative to the conventional capacitive fine-tuning of an LC-tank. The oscillator is injection locked to a time-delayed version of its resonating voltage and its frequency is modulated by manipulating the phase and amplitude of injected current. The injection strength can be programmed for the DCO step size to be as fine as 9 kHz at 4 GHz. Alternatively, with large injection strength, the tuning range can reach up to 200 MHz. The proposed oscillator is experimentally verified in TSMC 40 nm digital CMOS.
关键词： multi-stage noise ΣΔ (MASH),digitally controlled oscillator (DCO),digitally controlled delay (DCD),digital-to-frequency converter (DFC),All-digital PLL (ADPLL),digital phase rotator (DPR)
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Quantum Key Distribution Exploiting a Faraday Rotator and a Single Spad
摘要： Nowadays encryption is exploited for protecting information exchange in several applications. Nevertheless the security of commonly used algorithms of encryption is based on the extremely high computational cost required for message decryption. On the other hand, quantum key distribution (QKD) allows for exchanging a key between two users (Alice and Bob) in a way that has been proved as unconditional secure, thanks to the fundamental principles of quantum physics [1-3]. However to make the QKD a reliable and effective widespread solution, it is essential to reduce the cost and expand the scalability. In the present work we show the experimental validation of a novel implementation of the BB84 protocol, where Bob uses a Faraday rotator (FR) variable over four states and only one single-photon avalanche detector (SPAD), as schematized in Fig. 1(a). Alice transmit to Bob a stream of polarized single photons, obtained by a strongly attenuated laser followed by a polarization controller. The polarization of each photon is set by Alice in one state of polarization among four possible states (horizontal, vertical, diagonal, antidiagonal). A key bit is exchanged in a secure way through the quantum channel when Alice and Bob choose the same basis (either "rectilinear" or "diagonal") and a photon is detected by the SPAD after a polarizer set in a fixed state (e.g., vertical). Bob chooses the rotation angle of FR among four possible values (0°, 45°, 90°, 135°), hence making two binary choices. The first one (i.e., a rotation of either 0° or 45°) represents the choice of the measurement basis and is communicated to Alice through the public channel, while the second one (i.e., an additional rotation of either 0° or 90°) is maintained secret and allows Bob for determining the key bit.
关键词： Single SPAD,BB84 protocol,Quantum Key Distribution,Faraday Rotator
更新于2025-09-16 10:30:52