In this Letter, we propose a microstructured in-fiber optofluidic surface-enhanced Raman spectroscopy (SERS) sensor for the initial inspection of uremia through the detection of unlabeled urea and creatinine. As a natural microfluidic device, microstructured hollow fiber has a special structure inside. Through chemical bonds, the SERS substrate can be modified and grown on the surface of the suspended core. Here, the silver nanoparticles (Ag NPs) are embedded on the poly diallyl dimethyl ammonium chloride–modified graphene oxide sheet to achieve the self-assembled SERS substrate. The reduced distance between Ag NPs can increase the strong hot spots that generate enhanced Raman signals. Therefore, it can effectively detect the Raman signal of unlabeled trace uremic toxin analytes (urea, creatinine) inside the optical fiber. The results show that under simulated biophysical conditions, the limit detection (LOD) for urea is 10 − 4 M and the linearity is good, especially at the clinical conventional concentration range ( 2.5 − 6.5 × 10 − 3 M ). In addition, the online Raman detection of creatinine aqueous solution LOD is 10 − 6 M , which also has good linearity. Significantly, this Letter provides a microstructured optofluidic in-fiber Raman sensor for the preliminary detection of uremia, which will have good development prospects in the field of clinical biomedicine.

Nanophotonic engineering of light–matter interaction at subwavelength scale allows thermal radiation that is fundamentally different from that of traditional thermal emitters and provides exciting opportunities for various thermal‐photonic applications. We propose a new kind of integrated and electrically controlled thermal emitter that exploits layered metamaterials with lithography‐free and dielectric/metallic nanolayers. We demonstrate both theoretically and experimentally that the proposed concept can create a strong photonic bandgap in the visible regime and allow small impedance mismatch at the infrared wavelengths, which gives rise to optical features of significantly enhanced emissivity at the broad infrared wavelengths of 1.4–14 μm as well as effectively suppressed emissivity in the visible region. The electrically driven metamaterial devices are optically and thermally stable at temperatures up to ∼800 K with electro‐optical conversion efficiency reaching ∼30%. We believe that the proposed high‐efficiency thermal emitters will pave the way toward integrated infrared light source platforms for various thermal‐photonic applications and particularly provide a novel alternative for cost‐effective, compact, low glare, and energy‐efficient infrared heating.

The chaotic correlation fiber loop ring down system with loss compensation is initially developed. We use a chaotic laser to drive the fiber loop cavity and measure the autocorrelation coefficient ring down time of the chaotic laser. The chaotic laser is continuously injected into the fiber loop cavity with the erbium-doped fiber amplifier. The amplified chaotic laser acts as the signal for measurement of the ring down time and can stabilize the laser power in the loop cavity. It is different that only one pulse is transmitted in the pulsed fiber loop ring down technology with loss compensation. The chaotic correlation fiber loop ring down system with loss compensation is characterized in terms of the ring down baseline stability and the minimum detectable optical loss and can avoid the crosstalk of the signals. The detectable optical loss of 1.03 × 10 ^-4 Np and the baseline stability of 0.846% can be easily obtained.