We theoretically investigate the series-coupled fiber double-ring resonator is not exactly the same perimeter, that is, when the double-ring resonator cannot be completely in resonance state, the output characteristics and dispersion characteristics of spectrum and its manifestations. In this paper, we introduce light exhibits different spectral output characteristics through double-ring resonator, when the two rings’ length ratios are δ=1,1.1,1.5, 2. Among them, δ=2 is particularly representative. When the second resonator has the same parameters, the group refractive index of the double-ring resonator whose length ratio is 2 higher than the single ring resonator two or three orders, these results indicate that we could improve the sensitivity of the double-ring resonator because sensitivity is directly related to the group refractive.
KEYWORDS: Nanocrystals, Upconversion, Luminescence, Temperature sensors, Optical properties, Ytterbium, Thulium, Holmium, Temperature metrology, Far infrared
In the present paper, we first demonstrate NaLuF4: Yb3+: Tm3+/Ho3+ rare earth nanocrystals in microstructure hollow fiber. An analysis of the intense blue upconversion emission at 450 and 475 nm in Tm3+/Yb3+ codoped NaLuF4 under excitation power 0.65W available from solid laser emitting at 980nm, has been undertaken. Fluorescence intensity ratio (FIR) variation of temperature-sensitive blue upconversion emission at 450and 475 nm in this material was recorded in the temperature range from 300 to 345 K. The maximum sensitivity derived from the FIR technique of the blue upconversion emission is approximately 0.005 K−1. The results imply that Tm3+/Yb3+ codoped NaLuF4 is a potential candidate for the optical temperature sensor.
We compare the temperature sensitivity between the nested fiber ring resonator (NFRR) and the nested fiber ring resonator coupled Mach-Zehnder interferometer (NFRRCMZI). Theoretical results indicate that the temperature sensitivity of the NFRR is almost twelve times higher than that of NFRRCMZI with same parameters, hence complex MZI system can be removed and the whole sensing system will be more compatible without sacrificing the sensitivity. Taking feedback waveguide part as the sensing element in NFRR structure, the limitation of optical quality factor on sensitivity will be broken and arbitrary sensitivity can be acquired by easily setting different feedback waveguide length.
We theoretically investigate a basic structure that the series-coupled double ring resonator coupled two straight waveguide. We calculate the transmission function and phase shift through transfer matrix theory .The system consists of two rings, three straight waveguide and four couplers which the drop port and the though port are coupled to a bus waveguide .We obtain a tunable flat delay line which mitigates the deleterious effects of group delay dispersion in this structure through adjusting 4 coupling coefficient of the couplers, the attenuation factor of ring waveguide and the perimeter of 2 rings. The ability to realize the phenomenon is important for applications such as optical switching, and tunable bandwidth filter applications.
We theoretically analyze the electromagnetically induced transparency (EIT)-like spectrum in the Eye-like resonator configuration. The EIT-like spectrum results from the interference between the inner ring and the outer ring. In this paper, we obtain a tunable group delay and bandwidth of the transparency window through changing the coupling coefficients and the attenuation factors of the inner and the outer ring. The tunable group delay and the bandwidth will have potential application in optical switching or tunable delay lines and tunable bandwidth filter.
Indium doped zinc oxide (IZO) thin films were grown on sapphire substrate by radio frequency (RF/DC) magnetron sputtering technique. The structural characterization and surface morphology of IZO thin films were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The XRD results show that the samples exhibit polycrystalline characteristics and still retained wurtzite structure. The surface morphology of the samples reveals the average crystallite sizes are increased as indium content. In addition, the linear optical properties of IZO thin films were studied by UV-VIS spectrometer with wavelength range 200-900 nm. The high transmittances and the band gap values were observed in both thin films. Moreover, the nonlinear optical absorption and refraction of IZO thin films were investigated using nanosecond Z-scan technique. These samples show self-focusing optical nonlinearity and good two-photon nonlinear optical absorption behaviors. Therefore, these studies make the IZO thin films as the applications in nonlinear optical devices.
We theoretically and experimentally study an add-drop ring resonator to achieve tunable Fano resonance. In this system, the Fano resonance results from the interference of two beams from add and through port. The line shapes of the Fano resonances are tunable through controlling the phase bias of the two beams from add and through port. At the same time, add-drop ring resonator structure enabling the truly on/off switching mechanism is realized when the phase bias is 0 or π. The experimental results well agree with the theoretical calculation.
The interaction between plasmonic resonances, sharp modes, and light in nanoscale plasmonic systems often leads to Fano interference effects. This occurs because the plasmonic excitations are usually spectrally broad and the characteristic narrow asymmetric Fano line-shape results upon interaction with spectrally sharper modes. We investigate a plasmonic waveguide system using the finite-difference time-domain (FDTD) method, which consists of a metal-insulator-metal waveguide coupled with a rectangle and a ring cavity. Numerical simulations results show that the sharp and asymmetric Fano-line shapes can be created in the waveguide. Fano resonance strongly depends on the structural parameters. This has important applications in highly sensitive and multiparameter sensing in the complicated environments.
We theoretically investigate the series-coupled double micro-ring resonator as tunable optical delay line.
Tunable optical delay line can be achieved by tunable self-coupling coefficient and attenuation factor of
micro-ring waveguide. Through choosing suitable parameters of structure, the series-coupled double
micro-ring resonator can obtain flat delay line that mitigates the deleterious effects of group delay
dispersion.
KEYWORDS: Resonators, Mach-Zehnder interferometers, Sensors, Temperature metrology, Sensing systems, Temperature sensors, Signal to noise ratio, Phase shifts, Transparency
We theoretically investigate the properties of the series-coupled fiber double-ring resonator in a Mach–Zehnder interferometer as highly sensitive temperature sensor. By comparison of phase difference between two arms, we acquired suitable phase difference of 0.5π between two arms in a Mach–Zehnder interferometer for sharpest asymmetric line shape around the resonance wavelength. We also analyze the effect of parameters on the sensitivity and the detection limit by measuring the intensity change at a fixed wavelength. For the 30dB signal-to-noise ratio system, the sensitivity and the detection limit can achieve 720.8/°C and 4.16×10−6 °C, respectively. These results indicate that this structure is suitable for highly sensitive, compact and stable sensors.
The interaction between plasmonic resonances, sharp modes, and light in nanoscale plasmonic
systems often leads to Fano interference effects. This occurs because the plasmonic excitations are
usually spectrally broad and the characteristic narrow asymmetric Fano line-shape results upon
interaction with spectrally sharper modes. We investigate a plasmonic waveguide system using the
finite-difference time-domain method, which consists of a metal-insulator-metal waveguide coupled
with a circle and a disk cavity. Numerical simulations results show that the sharp and asymmetric
Fano-line shapes can be created in the waveguide. Fano resonance strongly depends on the structural
parameters. This has important applications in highly sensitive and multiparameter sensing in the
complicated environments.
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