In recent years, multicolor lasers have shown high potential for applications in many fields, such as white light source generation, biosensor or bioimaging, and optical communication, etc. Here, we use an optofluidic microbubble resonator (OFMBR) filled with a highly nonlinear liquid to obtain multicolor stimulated scatterings. By filling OFMBR with carbon disulfide and pumping it with nanosecond pulsed laser, a broadband visible supercontinuum spanning from 532 nm to 630 nm is generated due to the stimulated Raman scattering and stimulated Raman-Kerr scattering. This study opens the way towards potential application of multicolor or white light generation using optical nonlinear liquids.
We fabricated an opto-mechano-fluidic microbubble resonator (MBR) consisting of a dielectric silica shell and liquid metal core. Benefiting from the conductivity of the liquid metal GaInSn, Ohmic heating was carried out for the MBR by applying current to the liquid metal to change the temperature of the MBR. Optical whispering gallery mode (WGM) and the optomechanical surface wave mode were tuned mainly because the Ohmic heating changed the refractive index and the Young's modulus of the silica, respectively. The optomechanical radial breathing mode was tuned mainly because the Ohmic heating changed the velocity and density of the liquid metal GaInSn. In our experiment, the WGM mode was tuned approximately 1.22 nm. The optomechanical surface wave mode and radial breathing mode were tuned approximately 0.30 MHz and 0.23 MHz, respectively.
Biomaterial, such as proteins and deoxyribonucleic acid (DNA), which have many advantages such as biocompatibility and biodegradability, have been widely adopted as photonic device materials. In this study, we proposed and experimentally demonstrated an all-biomaterial whispering-gallery-mode (WGM) microbottle resonator. The quality factor of the fabricated protein microbottle resonator is on the order of 105. In addition, the entire process for preparing microbottle is simple and low-cost. Our work will open a door to explore various biomaterial and different bio-photonic device for biomedical applications.
We fabricated a polydimethylsiloxane (PDMS)-coated silica microbubble cavity with rich whispering gallery modes (WGMs). An electromagnetically induced transparency (EIT) window is realized through experimentally coupling a tapered fiber with the PDMS-coated microbubble resonator (MBR). There is a high-Q mode in the vicinity of a low-Q mode in transmission spectra. The experimental results prove that the high-Q mode performs a small redshift while the low-Q mode performs a large blueshift when the input power increases. This attributes to the negative thermo-optical coefficient (TOC) of PDMS and the positive TOC of silica. An EIT-like window is realized when these two modes are on-resonance with same frequency.
Raman lasing has been realized in different kinds of whispering gallery mode microresonators because of its high quality factors and relatively small mode volumes. The non-linear coefficient of carbon disulfide is much larger than that of silicon dioxide. In this paper, we fabricate a high quality factor silica microbubble resonator. In addition, we report on the realization of Raman lasing in an empty silica microbubble resonator. Moreover, Raman lasing in carbon disulfide filled optofluidic microbubble resonator at pump wavelengths of 950 nm is also implemented.
We experimentally demonstrate a high sensitivity temperature sensor based on packaged microdroplet whispering gallery mode (WGM) resonator. Fabrication process of the packaged microdroplet resonator is easy and controllable. The sensitivity and the electric field intensity distribution of different radial modes are calculated and analyzed by Mie theory. The measured temperature sensitivity is over 200 pm/ °C, due to the mode distribution of microdroplet resonator and high thermo-optic coefficient of dimethyl sulfoxide (DMSO). The proposed packaged microdroplet resonator has the superiority in the high sensitivity and robust property, which exhibit good potential in regards to future integrated photonic devices based sensors.
KEYWORDS: Sensors, Optical microcavities, Biosensors, Refractive index, Simulation of CCA and DLA aggregates, Optofluidics, Biological and chemical sensing, Chemical analysis, Target detection, Biosensing
We proposed and experimentally demonstrated a sensitive, label-free, real-time and low-cost optofluidic microcavity biosensor for DNA detection. The change of whispering gallery mode (WGM) resonant wavelength is monitored by data acquisition card in real-time. The experimental results show that the biosensor can significantly distinguish the non-complementary single strand (ssDNA), single nucleotide mismatch ssDNA, and target ssDNA. In addition, a sensing mechanism based on WGM coupling depth was also experimentally demonstrated which would have potential for detection of biological and chemical analytes in the future.
Luneburg-sphere (LS) is a spherically symmetric sphere with three-dimensional graded-refractive-index structure which can focus parallel beam to a perfect point on the sphere surface. Recent research shows that microsphere can generate super-resolution focusing beyond diffraction limit. Herein a quasi-Luneburg-lens can be used as an optically transparent microsphere for the super-resolution imaging. In this paper, the finite element model is used to investigate the optical properties of the Luneburg-lens. Our simulation results demonstrated that its focus size is below the conventional diffractive limit in the visible spectrum. An effective method of application of a quasiLuneburg-lens is proposed and discussed. Besides super-resolution imaging, Luneburg-lens have the potential applications in nanolithography, nanomedicine areas as well.
We proposed and theoretically investigated a hybrid plasmonics waveguide consisting of a tiptilted quadrate nanowire, which was embedded in a low-permittivity dielectric and placed on a metal substrate with a small gap distance. Due to the corner effect, the hybrid mode with extremely local field enhancement has the long propagation length and strong coupling strength between the dielectric nanowire and metal. By employing the simulations with different geometric parameters, the proposed waveguide can obtain better performances than the previous hybrid plasmonics waveguide, particularly in the subwavelength confinement (as small as λ2/1600), long-range propagation (millimeter range), and optical trapping forces (2.12 pN/W). The use of a naturally dielectric wedge tip of quadrate nanowire that can be chemically synthesized provides an efficient approach to circumvent the fabrication difficulty of shape wedge tips. The present structure provides an excellent platform for nanophotonic waveguides, nanolasers, nanoscale optical tweezers, and biosensing.
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