分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Microlaser with multiple lasing bands is critical in various applications, such as full-colour display, optical communications and computing. Here, we propose a simple and efficient method for homogeneously doping rare earth elements into a silica whispering-gallery-mode microcavity. By this method, we demonstrate simultaneous and stable lasing covering ultraviolet, visible and near-infrared bands in an ultrahigh-Q (exceeding 108) Er-Yb co-doped silica microsphere under room temperature and continuous-wave pump for the first time. The lasing thresholds of the 380, 410, 450, 560, 660, 800, 1080 and 1550 nm-bands are estimated to be 380, 150, 2.5, 12, 0.17, 1.7, 10 and 38 {\mu}W, respectively, where the lasing in the 380, 410 and 450 nm-bands by Er element have not been separately demonstrated under room temperature and continuous-wave pump until this work. This ultrahigh-Q doped microcavity is an excellent platform for high-performance multi-band microlasers, ultrahigh-precise sensors, optical memories and cavity-enhanced light-matter interaction studies.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： We theoretically propose and study in-plane anisotropic acoustic phonon polaritons (APhPs) based on a layered structure consisting of a monolayer (or few layers) {\alpha}-phase molybdenum trioxide ({\alpha}-MoO3) sandwiched between two metal layers. We find that the APhPs in the proposed sandwiched structures are a canalization (highly directional) electromagnetic mode propagating along with the layers and at the same time exhibit extreme electromagnetic-field confinement surpassing any other type of phonon-polariton modes. When a double layer of {\alpha}-MoO3 is sandwiched by two Au layers, twisting the two {\alpha}-MoO3 layers can adjust the interlayer polaritonic coupling and thus manipulate the in-plane propagation of the highly confined APhPs. Our results illustrate that the metal-MoO3-metal sandwiched structures are a promising platform for light guiding and manipulation at ultimate scale.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： White laser covering the visible color spectrum is critical in various applications including vivid display, holographic imaging and light-based version of Wi-Fi, but it is still challenging to realize the white microlaser due to the rigorous requirement in the balance between the optical gain and the feedback at different wavelengths. Here, we employ Tm, Er and Yb ions corporately for the upconversion white lasing in a single ultrahigh quality (Q) (up to 108) doped microcavity, where the thresholds of the red, green and blue lasers are about 90, 500 and 300 {\mu}W, respectively. To the best of our knowledge, it is the first rare-earth elements based room-temperature, continuous-wave white microlaser, which exhibits relatively stable chromaticity over 180 minutes, making it possible for practical applications.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Encircling an exceptional point (EP) in a parity-time (PT) symmetric system has shown great potential for chiral optical devices, such as chiral mode switching for symmetric and anti-symmetric modes. However, the chiral switching for polarization states has never been reported although chiral polarization manipulation has significant applications in imaging, sensing, and communication etc. Here inspired by the anti-PT symmetry, we demonstrate an on-chip chiral polarizer by constructing polarization-coupled anti-PT symmetric system for the first time. The transmission axes of the chiral polarizer are different for forward and backward propagation. A polarization extinction ratio of over 10 dB is achieved for both propagating directions. Moreover, a telecommunication experiment is performed to demonstrate the potential applications in polarization encoding signals. It provides a novel functionality for encircling-an-EP parametric evolution and offer a new approach for on-chip chiral polarization manipulation.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Integrated optical filter based on microring resonators plays a critical role in many applications, ranging from wavelength division multiplexing and switching to channel routing. Bandwidth tunable filters are capable of meeting the on-demand flexible operations in complex situations, due to their advantages of scalability, multi-function, and energy-saving. It has been investigated recently that parity-time (PT) symmetry coupled-resonant systems can be applied to the bandwidth-tunable filters. However, due to the trade-off between the bandwidth-tunable contrast ratio and insertion loss of system, the bandwidth-tunable contrast ratio of this method is severely limited. Here, the bandwidth-tunable contrast ratio is defined as the maximum bandwidth divided by the minimum bandwidth. In this work, we show that high bandwidth-tunable contrast ratio and low insertion loss of system can be achieved simultaneously by increasing the coupling strength between the input port and the resonant. System characterizations under different coupling states reveal that the low insertion loss can be obtained when the system initially operates at the over-coupling condition. A high bandwidth-tunable contrast ratio PT-symmetry band-pass filter with moderate insertion loss is shown on the Silicon platform. Our scheme provides an effective method to reduce the insertion loss of on-chip tunable filters, which is also applicable to the high-order cascaded microring systems.
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