Long cylinders, such as optical fibers, are some of the most widely used photonic devices. The radius and refractive index of these fibers are therefore fundamentally important parameters in determining their performance. We have developed a method to determine the absolute radius, refractive index, and chromatic dispersion of a long cylinder using only the resonance wavelengths of the whispering gallery modes around its circumference for two different polarizations. Since this method only requires the measurement of resonance wavelengths, it is non-destructive and it can be performed using standard equipment. As a proof-of-concept, we demonstrate the method on a $125μm$ optical fiber and an $80μm$ borosilicate capillary fiber with thick walls, obtaining values for the diameter and the refractive index with an accuracy of $2 nm$ and $2\times 10^{-5}$, respectively.
Temperature-dependent absolute refractive index measurements of synthetic fused silica
利用NASA戈达德航天飞行中心的低温高精度折射测量系统（CHARMS），我们测量了5个样品的绝对折射率，这些样品取自一个非常大的康宁7980熔融石英晶锭，温度范围从30 K到310 K，波长范围从0.4微米到2.6微米，绝对不确定度为+/-1 x 10^-5。热光系数（dn/dT）导出值的统计变化在+/-2 x 10^-8/K水平。绝对折射率，色散和热光系数的图形和表格数据，提出了选定的波长和温度，以及估计的不确定性指数。温度相关的Sellmeier拟合测得的折射率的系数也被提出，以允许准确的插值指数到其他波长和温度。我们将我们的结果与独立调查（使用干涉测量技术测量折射率随温度的变化）的结果进行了比较，该调查的样品是由与我们的棱镜为支持开普勒任务而准备的相同材料制成的。我们还比较了我们的研究结果与稀疏的低温指数数据从测量这种材料的文献。
We describe a high-speed interferometric method, using multiple angles of incidence and multiple wavelengths, to measure the absolute thickness, tilt, the local angle between the surfaces, and the refractive index of a fluctuating transparent wedge. The method is well suited for biological, fluid and industrial applications.
Precise measurements of the geometrical thickness of a sample and its refractive index are important for materials science, engineering, and medical diagnosis. Among the possible non-contact evaluation methods, optical interferometric techniques possess the potential of providing superior resolution. However, in the optical frequency region, the ambiguity in the absolute phase-shift makes it difficult to measure these parameters of optically thick dispersive materials with sufficient resolution. Here, we demonstrate that dual frequency-comb spectroscopy can be used to precisely determine the a…
Temperature dependent refractive index of silicon and germanium
硅和锗可能是固态器件技术以及最近的微加工和纳米技术背景下最广为人知的两种半导体材料。同时，这两种材料在红外镜头设计领域也有重要的应用。为这两种材料透射的波长范围设计的光学仪器在冷却至低温时实现最佳性能，以增强来自场景的信号超过仪器背景辐射。为了实现在低温下使用硅和锗的高质量透镜设计，我们使用NASA戈达德太空飞行中心的低温高精度折射测量系统（CHARMS）测量了这两种材料的多个棱镜的绝对折射率，作为波长和温度的函数。对于硅，我们报告的绝对折射率和热光系数（dn/dT）在温度范围从20至300 K，波长从1.1至5.6微米，而对于锗，我们覆盖的温度范围从20至300 K和波长从1.9至5.5微米。我们将我们的测量结果与文献中的其他测量结果进行比较，并根据我们的数据提供依赖于温度的Sellmeier系数，以便将指数精确插值到其他波长和温度。引用文献中这两种材料折射率的各种数值，我们重申，当绝对精度要求大于+/-5 x 10^-3时，测量来自同一批原材料的样品的折射率是非常重要的。
Multiplexed, specific and sensitive detection of antigens is critical for the rapid and accurate diagnosis of disease and the informed development of personalized treatment plans. Here, we show that polymer microsphere lasers can be used as photonic sensors to monitor and quantify direct surface binding of biomolecules via changes in the refractive index. The unique spectral signature of each individual laser can be used to find their size and effective refractive index which adds a new encoding dimension when compared to conventional fluorescent beads. We utilize antibody-functionalized micro…
The nonlinear optical properties of the high index nanoparticles are boosted at the anapole state. Researchers intensively study this phenomenon as promising for various applications. In this work, the nonlinear optical Kerr effect of disordered and square lattice metasurfaces of GaP nanodisks is investigated as a function of the disk size in the vicinity of the anapole state at the wavelength of 532 nm. When the sizes of the nanodisks are close to the anapole state, the effective second order refractive index of the metasurface increases exponentially. On approaching the anapole state, the si…
Polaritonic materials, owing to a strong phonon-polariton resonance in the THz and far-infrared parts of the electromagnetic spectrum, offer both high-index dielectric and metallic response in this regime. This complex response makes them suitable candidates for the design of metamaterial-related phenomena and applications. Here we show that one type of polaritonic-material-based structures that are particularly suitable for the achievement of a wide range of metamaterial properties are systems of polaritonic rods. To study the interplay between the material and the structural resonances in su…
Dynamic analysis of refractive index evolution and diffraction properties during single-photon polymerization of photopolymers for micro-optical applications
The dependence of the semiconductor laser wavelength on the pump current is a well-known phenomenon, which is generally attributed to a change in the refractive index of the active layer due to carrier injection. This effect is usually considered to be a drawback as it causes frequency chirping of the pulses produced via direct current modulation. Here, we show that at high values of thermal resistance of a laser diode, the lasing wavelength is red-shifted due to the change of the refractive index caused by a thermal effect and this shift may significantly exceed (in absolute value) the blue s…
Electrically-tunable optical properties in materials are desirable for many applications ranging from displays to lasing and optical communication. In most two-dimensional thin-films and other quantum confined materials, these constants have been measured accurately. However, the optical constants of single wall nanotubes (SWCNT) as a function of electrostatic tuning are yet to be measured due to lack of electronic purity and spatial homogeneity over large areas. Here, we measure the basic optical constants of ultrathin high-purity (>99%) semiconducting single wall carbon nanotube (s-SWCNT) fi…
