Optical Waveguide Theory

2D Layered Materials: Synthesis, Nonlinear Optical Properties, and Device Applications

Demand for accessible and affordable healthcare for infectious and chronic diseases present significant challenges for providing high-value and effective healthcare. Traditional approaches are expanding to include point-of-care (POC) diagnostics, bedside testing, and community-based approaches to respond to these challenges.1 Innovative solutions utilizing recent advances in mobile technologies, nanotechnology, imaging systems, and microfluidic technologies are envisioned to assist this transformation.

Infectious diseases have considerable economic and societal impact on developing settings. For instance, malaria is observed more commonly in sub-Saharan Africa and India.2 The societal impact of acquired immune deficiency syndrome (AIDS) and tuberculosis is high, through targeting adults in villages and leaving behind declining populations.3 In resource-constrained settings, it is estimated that about 32% of the disease burden is from communicable diseases such as respiratory infections, AIDS, and malaria, while 43% of the burden is from noncommunicable diseases, such as cardiovascular diseases, neuropsychiatric conditions, and cancer.4 Developing diagnostic platforms that are affordable, robust, and rapid-targeting infectious diseases is one of the top priorities for improving healthcare delivery in the developing world.5 The early detection and monitoring of infectious diseases and cancer through affordable and accessible healthcare will significantly reduce the disease burden and help preserve the social fabric of these communities. Further, improved diagnostics and disease monitoring technologies have potential to enhance foreign investment, trade, and mobility in the developing countries.6

Highly sensitive and specific lab assays such as cell culture methods, polymerase chain reaction (PCR), and enzyme-linked immunosorbent assay (ELISA) are available for diagnosis of infectious diseases in the developed world. They require sample transportation, manual preparation steps, and skilled and well-trained technicians. These clinical conventional methods provide results in several hours to days, precluding rapid detection and response at the primary care settings. Another diagnostic challenge is identifying multiple pathogens. Since common symptoms like sore throat and fever can be caused by multiple infectious agents (e.g., bacteria and viruses), it is important to accurately identify the responsible agent for targeted treatment. Therefore, high-throughput sensors for multiplexed identification would help improve patient care.7

Medical instruments in centrally located institutions in the developed world rely on uninterrupted electricity and running water and require controlled environmental conditions. It may not be viable to satisfy some of these criteria in some POC settings, where well-trained healthcare personnel are not available and clean water access is unreliable.7,8 Further, in remote settings without infrastructure, rain and dust can act as contaminants.7 Diagnostic devices for POC testing in these settings are identified by the World Health Organization to be affordable, sensitive, user-friendly, specific to biological agents, and providing rapid response to small sample volumes.9 Optical biosensor devices are emerging as powerful biologic agent detection platforms satisfying these considerations.10

Optical sensing platforms employ various methods, including refractive index change monitoring, absorption, and spectroscopic-based measurements.11 Optical sensors that are based on refractive index monitoring cover a range of technologies, including photonic crystal fibers, nano/microring resonator structures, interferometric devices, plasmonic nano/micro arrays, and surface plasmon resonance (SPR)-based platforms.11,12 The latter two are plasmonic-based technologies. Plasmonics is an enabling optical technology with applications in disease monitoring, diagnostics, homeland security, food safety, and biological imaging applications. The plasmonic-based biosensor platforms along with the underlying technologies are illustrated in the Figure ​Figure1.1. Here, we reviewed SPR, localized surface plasmon resonance (LSPR), and large-scale plasmonic arrays (e.g., nanohole arrays).



Figure 1

Plasmonic-based technologies for versatile biosensor applications. SPR stands for surface plasmon resonance, LSPR for localized surface plasmon resonance, SPRi for surface plasmon resonance imaging, and SERS for surface-enhanced Raman scattering.

https://canarycenter.stanford.edu/content/dam/sm/canarycenter/documents/research/bamm-lab/ChemicalReview.pdf

Advances in Plasmonic Technologies for Point of Care Applications

We present and numerically characterize a closed-form multi-core holey fiber based plasmonic sensor. The coupling properties of the specific modes are investigated comprehensively by the finite element method. It is found that not only phase matching but also loss matching plays a key role in the coupling process between the fundamental mode and plasmonic mode. The coupling transforms from incomplete coupling to complete coupling with increasing analyte RI. An average sensitivity of 2929.39nm/RIU in the sensing range 1.33-1.42, and 9231.27nm/RIU in 1.43-1.53 with high linearity is obtained. The dynamic sensing range is the largest among the reported holey fiber based plasmonic sensors, to the best of our knowledge.

A multi-core holey fiber based plasmonic sensor with large detection range and high linearity

An Er-doped mode-locked fiber laser with a tapered two-mode fiber for wavelength selection has been demonstrated. Depending on the free spectral range of TTMF filter, the central wavelengths of the mode-locking operation can be switched.

Wavelength Switchable Mode-Locked Fiber Laser with Tapered Two-Mode Fiber

In this paper, we propose an improved method to reconstruct object shape for shape sensors based on fiber bragg grating (FBG), where FBG array is embedded in silicone gel as protection shell and glued on rubber tape surface to distinguish bending direction. The calibration experiments of FBG are presented to ensure relative precise conversion between FBG wavelength offsets and bending curvature. In the improved method, spline interpolation technique instead of traditional linear technique is employed to characterize relationship between bending curvature and arc length, with Frenet-serret equation used in the procedure of object shape reconstruction. The experiment results show that spline interpolation technique induces lower error than linear interpolation technique, which verifies that an improvement in object shape reconstruction can be achieved by employing spline interpolation technique.

New Interpolation Method for Shape Sensors Based on Fiber Bragg Grating

Label-free optical biosensor based on a dual-core microstructured polymer optical fiber

We demonstrated an ultrasensitive temperature sensor based on a unique fiber Fabry-Perot interferometer (FPI). The FPI was created by means of splicing a mercury-filled silica tube with a single-mode fiber (SMF). The FPI had an air cavity, which was formed by the end face of the SMF and that of the mercury column. Experimental results showed that the FPI had an ultrahigh temperature-sensitivity of up to -41 nm/°C, which was about one order of magnitude higher than those of the reported FPI-based fiber tip sensors. Such a FPI temperature sensor is expected to have potential applications for highly-sensitive ambient temperature sensing.

Ultrahigh-sensitivity temperature sensor based on in-fiber Fabry-Perot interferometer

The utility model discloses a single -frequency narrowband fiber laser based on high circularity 3D rotation symmetry microcavity, include: the semiconductor laser pumping source, wavelength division multiplexer, optical isolator, the tombarthite doped fiber, polarization controller and optical coupler, still include high circularity microballon chamber tapered fiber coupling unit, the semiconductor laser pumping source links to each other with optical isolator through wavelength division multiplexer, and link to each other with the tombarthite doped fiber through optical isolator's output, the output of tombarthite doped fiber loops through polarization controller, high circularity microballon chamber tapered fiber coupling unit, a wavelength division multiplexer, synthetic chamber is closed to last being linked to each other with the wavelength division multiplexer input by the optical coupler output. The utility model discloses a high circularity microballon chamber tapered fiber coupling unit carries out the frequency -selecting, and the super narrow bandwidth echo wall mould resonance register for easy reference that high circularity microballon intracavity formed makes output laser have the advantage of super narrow bandwidth, has still that the coherence is good, stability height, compact structure, with low costs a, advantage such as the loss is little.

Bing Sun

Papers

Wavelength Switchable Mode-Locked Fiber Laser with Tapered Two-Mode Fiber

New Interpolation Method for Shape Sensors Based on Fiber Bragg Grating

Label-free optical biosensor based on a dual-core microstructured polymer optical fiber

Ultrahigh-sensitivity temperature sensor based on in-fiber Fabry-Perot interferometer

Single -frequency narrowband fiber laser based on high circularity 3D rotation symmetry microcavity