The increasing capability for manufacturing a wide variety of optoelectronic devices from polymer and polymer–silicon hybrids, including transmission fibre, modulators, detectors and light sources, suggests that organic photonics has a promising future in communications and other applications.

Organic photonics for communications

Fiber-optic biosensors (FOBS) are optical fiber-derived devices which use optical field to measure biological species such as cells, proteins, and DNA. Because of their efficiency, accuracy, low cost, and convenience, FOBS are promising alternatives to traditional immunological methods for biomolecule measurements. Tapered fiber-optic biosensors (TFOBS) are a type of FOBS which rely on special geometries to expose the evanescent field to interact with samples. In order to amplify sensitivity and selectivity, TFOBS are often used with various optical transduction mechanisms such as changes in refractive index, absorption, fluorescence, and Surface Plasmon Resonance. In this review, the basic principles of TFOBS are summarized. Various common geometries for evanescent sensing and the influence of geometric parameters on optical principles are reviewed. Finally, a detailed account of the studies done to date for biomolecules detection using TFOBS will be provided. © 2007 Elsevier B.V. All rights reserved.

A review of fiber-optic biosensors

Fabrication of large-area clean graphene sheets is the first step toward the development of high-performance applications in surface chemistry and biotechnology as well as in high-mobility electronics. Here we demonstrate the clean transfer of graphene grown by chemical vapor deposition on Cu foil, with surface cleanness defined by transmission electron microscopy (TEM) in combination with Raman scattering on the same position of suspended graphene sheets. For clean graphene, the Raman spectra exhibit distinctive features that can explicitly discriminate from that of graphene covered with a thin layer of amorphous carbon such as residual poly(methyl methacrylate) (PMMA). By applying this technique to graphene sheets with various degrees of surface cleanness, we show that the quantitative characterization of the thickness of surface contaminants is possible based on multiple reflections and interference of light in samples.

Clean transfer of graphene for isolation and suspension.

The recent advances of polymer technology allowed the introduction of plastic optical fiber in sensor design. The advantages of optical metrology with plastic optical fiber have attracted the attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented.

Optical sensors based on plastic fibers.

Solid-state organic amplifiers and lasers are attractive for hybrid integration due to their compatibility with different material platforms, straightforward processing, and possibility to optimize easily their optical and electronic properties by molecular engineering. Advances in the gain medium design and synthesis in combination with new resonator architectures led to tremendous improvements in temporal and spectral properties, lifetime stability, gains produced and operating threshold powers, which triggered interest in their use for a broad range of integrated photonic applications. In this contribution, the current state-of-the-art in the field of organic solid-state amplifiers and lasers is reviewed from the aspects of fabrication technology, gain materials, and device performance. Furthermore, examples of the progress of this technology from a laboratory curiosity to one that demonstrates practical integrated photonic applications are highlighted. An outlook is also provided on research areas and applications that are likely to shape further developments of this technology.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/lpor.201100034

Organic solid-state integrated amplifiers and lasers

Polymethyl methacrylate (PMMA) optical fibres are fabricated by a preform drawing process. The Raman spectra of PMMA fibres are recorded using a diode pumped solid state laser emitting at 532 nm and a CCD-spectrograph in the 400‐3800 cm −1 range. The variation of the Raman intensity with the length of the optical fibre is studied. Investigations are carried out on the variation of FWHM of the Raman peak at 2957 cm −1 with the length of the optical fibre and pump power. The differential scattering cross section and gain coefficient of the Raman peak at 2957 cm −1 in PMMA are calculated in relation to that of toluene.

https://iopscience.iop.org/article/10.1088/1464-4258/10/5/055303/pdf

Raman spectra of polymethyl methacrylate optical fibres excited by a 532 nm diode pumped solid state laser

The design and development of a fibre optic evanescent wave refractometer for the detection of trace amounts of paraffin oil and palm oil in coconut oil is presented. This sensor is based on a side-polished plastic optical fibre. At the sensing region, the cladding and a small portion of the core are removed and the fibre nicely polished. The sensing region is fabricated in such a manner that it sits perfectly within a bent mould. This bending of the sensing region enhances its sensitivity. The oil mixture of different mix ratios is introduced into the sensing region and we observed a sharp decrease in the output intensity. The observed variation in the intensity is found to be linear and the detection limit is 2% (by volume) paraffin oil/palm oil in coconut oil. The resolution of this refractometric sensor is of the order of 10 −3 . Since coconut oil is consumed in large volumes as edible oil in south India, this fibre optic sensor finds great relevance for the detection of adulterants such as paraffin oil or palm oil which are readily miscible in coconut oil. The advantage of this type of sensor is that it is inexpensive and easy to set up. Another attraction of the side-polished fibre is that only a very small amount of analyte is needed and its response time is only 7 s.

/pdf/fibre-optic-sensor-for-the-detection-of-adulterant-traces-in-1zncytt6od.pdf

Fibre optic sensor for the detection of adulterant traces in coconut oil

The fabrication and characterization of a Rhodamine 6G-doped polymer optical fiber amplifier have been carried out. Two different schemes were employed to characterize the optical fiber: the stripe illumination technique to study the fiber as a gain medium and another technique to study its performance as an amplifier. We observed a spectral narrowing from 42 to
7 nm when the pump energy was increased to 6 mJ in the stripe illumination geometry. A gain of
18 dB was obtained in the amplifier configuration. The effects of pump power and dye concentration on the performance of the fiber as an amplifier were also studied.

/pdf/fabrication-and-characterization-of-dye-doped-polymer-1ej57k4nb3.pdf

Fabrication and characterization of dye-doped polymer optical fiber as a light amplifier.

Multimode laser emission is observed in a polymer optical fiber doped with a mixture of Rhodamine 6G (Rh 6G) and Rhodamine B (Rh B) dyes. Tuning of laser emission is achieved by using the mixture of dyes due to the energy transfer occurring from donor molecule (Rh 6G) to acceptor molecule (Rh B). The dye doped poly(methyl methacrylate)-based polymer optical fiber is pumped axially at one end of the fiber using a 532 nm pulsed laser beam from a Nd:YAG laser and the fluorescence emission is collected from the other end. At low pump energy levels, fluorescence emission is observed. When the energy is increased beyond a threshold value, laser emission occurs with a multimode structure. The optical feedback for the gain medium is provided by the cylindrical surface of the optical fiber, which acts as a cavity. This fact is confirmed by the mode spacing dependence on the diameter of the fiber.

/pdf/multimode-laser-emission-from-dye-doped-polymer-optical-5f3sttxq88.pdf

Multimode laser emission from dye doped polymer optical fiber

Optical fiber based laser induced fluorescence (LIF) measurements were carried out using Rhodamine B to analyze two different species of bacteria, a Gram-positive bacteria namely Bacillus smithii, and Vibrio alginolyticus, a Gram-negative bacteria. The fiber sensor was clearly able to distinguish between the two species of bacteria. Quenching effect of the dye Rhodamine B by Bacillus smithii was observed. The effect of dye on the samples was also studied in detail.

/pdf/laser-induced-fluorescence-based-optical-fiber-probe-for-3ukxranjny.pdf

M. Sheeba

Papers

Raman spectra of polymethyl methacrylate optical fibres excited by a 532 nm diode pumped solid state laser

Fibre optic sensor for the detection of adulterant traces in coconut oil

Fabrication and characterization of dye-doped polymer optical fiber as a light amplifier.

Multimode laser emission from dye doped polymer optical fiber

Laser induced fluorescence based optical fiber probe for analyzing bacteria