Name: design and fabrication of an optical fiber made of water
Uploaded: 2018-11-08T12:30:00
Description: Watch this Scientific Journal Video about Design and Fabrication of an Optical Fiber Made of Water at JoVE.com

This research was supported by the Israeli Ministry of Science, Technology &#38; Space; ICore: the Israeli Excellence center &#39;Circle of Light&#39; grant no. 1802/12, and by the Israeli Science Foundation grant no. 2013/15. The authors thank Karen Adie Tankus (KAT) for the helpful editing.

CAUTION: This experiment involves high voltage. It is the reader&#39;s responsibility to verify with the safety authorities that their experiment follows regulations before turning on the high voltage.
NOTE: Any kind of polar liquid can be utilized to produce liquid fibers, such as ethanol, methanol, acetone, or water. The polarity of the liquid dictates the stability and diameter of the created fiber23,24. For best results, use deioni...

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F., Ramek, M., Woisetschl&#228;ger, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methanol,+Ethanol+and+Propanol+in+EHD+liquid+bridging.">Methanol, Ethanol and Propanol in EHD liquid bridging.</a> Journal of Physics: Conference Series. 329, 12003 (2011).</li><li>Douvidzon, M. L., Maayani, S., Martin, L. L., Carmon, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light+and+Capillary+Waves+Propagation+in+Water+Fibers.">Light and Capillary Waves Propagation in Water Fibers.</a> Science Reports. 7, 16633 (2017).</li><li>. Water Fibers Available from: <a target="_blank" href="https://arxiv.org/abs/1609.03362">https://arxiv.org/abs/1609.03362</a> (2016)</li></ol>

To conclude, the major advantage and uniqueness of this technique is creating a fiber which hosts three different kinds of waves: capillary, acoustic, and optical. All three waves oscillate in different regimes, opening the possibility for multi-wave detectors. As an example, airborne nanoparticles affect the surface tension of liquids. Already at the current stage, it is possible to monitor changes in the surface tension through variations in the capillary eigenfrequency. Additionally, water-walled devices are a million...

Since the breakthrough of optical fibers in communication, awarded with a Nobel prize in 20091, a series of fiber-based applications grew alongside. Nowadays, fibers are a necessity in laser surgeries2, as well as in coherent X-ray generation3,4, guided-sound5 and supercontinuum6. Naturally, the research on fiber optics expanded from utilizing solids into exploiting liquids for optical wave guiding, where liquid-filled microchannels and laminar flow combine the transportation properties of a liquid with the advantages of optical interrogation7,8,9. However, these devices clamp the liquid between solids and, therefore, forbid it to express its own wave character, known as capillary wave.
Capillary waves, similar to those seen when throwing a stone into a pond, are an important wave in nature. However, due to the obstacles of controlling a liquid without dampening its surface through channels or solids, they are hardly utilized for detection or application. In contrast, the device presented in this protocol has no solid boundaries; it is surrounded by and flows in air, allowing, therefore, capillary waves to develop, propagate, and interact with light.
To fabricate a water fiber, it is necessary to go back to a technique known as the floating water bridge, first reported in 189310, where two beakers filled with distilled water and connected to a high-voltage source will form a fluidic, water thread-like connection between them11. Water bridges can reach up to a length of 3 cm12 or be as thin as 20 nm13. As for the physical origin, it has been shown that surface tensions, as well as dielectric forces, are both responsible for carrying the bridge&#39;s weight14,15,16. To activate the water bridge as a water fiber, we couple light in with an adiabatically tapered silica fiber17,18 and out with a silica fiber lens19. Such a device can host acoustical, capillary, and optical waves, making it advantageous for multi-wave detectors and lab-on-chip20,21,22 applications.

<table border="0" cellpadding="0" cellspacing="0" width="1035">
	<tbody>
		<tr height="21">
			<td align="left" height="21" style="height:21px;width:497px;">Deioniyzed Water&#160;</td>
			<td style="width:252px;"></td>
			<td style="width:119px;"></td>
			<td align="left" style="width:167px;">18MOhm resistance</td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;width:497px;">Micropipettes, Borosilicate Glass, round, inner diameter 850 micron</td>
			<td align="left" style="width:252px;">Produstrial.com</td>
			<td align="left" style="width:119px;">#133260</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;width:497px;">Micropipettes, Borosilicate Glass, round, inner diameter 150 micron</td>
			<td align="left" style="width:252px;">Produstrial.com</td>
			<td align="left" style="width:119px;">#133258</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;width:497px;">High voltage, low current source, 3kV with 5 mA.</td>
			<td align="left" style="width:252px;">Bertan</td>
			<td align="left" style="width:119px;">Model 215</td>
			<td></td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;width:497px;">High voltage, low current source,&#160; 8 kV with 0.25 mA.</td>
			<td align="left" style="width:252px;">Home build</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;">Optical fiber</td>
			<td align="left" style="width:252px;">Corning</td>
			<td align="left" style="width:119px;">HI 780 C</td>
			<td align="left">5 meter</td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;">Optical fiber</td>
			<td align="left" style="width:252px;">Thorlabs</td>
			<td align="left" style="width:119px;">FTO 30</td>
			<td align="left">5 meter</td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;">Optical fiber</td>
			<td align="left" style="width:252px;">Thorlabs</td>
			<td align="left" style="width:119px;">FTO 30</td>
			<td align="left">5 meter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#160;Fiber coupled laser</td>
			<td align="left" style="width:252px;">FIS</td>
			<td align="left" style="width:119px;">SMF 28E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;width:497px;">Photoreceiver</td>
			<td align="left" style="width:252px;">New Port/ New Focus</td>
			<td align="left" style="width:119px;">1801-FS</td>
			<td align="left">with fiber connection</td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;">Oscilloscope</td>
			<td align="left" style="width:252px;">Agilent Technologies</td>
			<td align="left" style="width:119px;">DSO-X 3034A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;">2 Degree of freedom tilt stagestage</td>
			<td align="left" style="width:252px;">New Port/ New Focus</td>
			<td align="left" style="width:119px;">M-562F-TILT</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">3Degree of freedom linear micro translation stage&#160;&#160;</td>
			<td align="left" style="width:252px;">New Port/ New Focus</td>
			<td align="left" style="width:119px;">M-562F-XYZ</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">A set of magnets</td>
			<td style="width:252px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">Objective 5X</td>
			<td align="left" style="width:252px;">Mitutoyo&#160;</td>
			<td align="left" style="width:119px;">MY5X-802</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">Objective 20 x</td>
			<td align="left" style="width:252px;">Mitutoyo&#160;</td>
			<td align="left" style="width:119px;">MY20X-804</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">Zoom</td>
			<td align="left" style="width:252px;">Navitar</td>
			<td align="left" style="width:119px;">12x Zoom</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:497px;">Microscope tube</td>
			<td align="left" style="width:252px;">Navitar</td>
			<td align="left" style="width:119px;">1-6015 standard tube</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">Isopropanol</td>
			<td align="left" style="width:252px;">Sigma Aldrich</td>
			<td align="left" style="width:119px;">67-63-0</td>
			<td align="left">Spec Grad</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">2 x Bare Fiber holder</td>
			<td align="left" style="width:252px;">Thorlabs</td>
			<td align="left" style="width:119px;">T711-250</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">2 x Translational Stage</td>
			<td align="left" style="width:252px;">Thorlabs</td>
			<td align="left" style="width:119px;">DT12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">Block of PMMA for fabricating the water reservoir and pipette holder</td>
			<td style="width:252px;"></td>
			<td align="left" style="width:119px;"></td>
			<td align="left">150 x 60 x 10 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">PTFE-Tape</td>
			<td align="left" style="width:252px;">Gufero</td>
			<td align="right" style="width:119px;">240453</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:497px;">Fiber coupled, cw Laser Light Source</td>
			<td align="left" style="width:252px;">New Port/ New Focus</td>
			<td align="left" style="width:119px;">TLB-6712</td>
			<td align="left">765-781 nm</td>
		</tr>
	</tbody>
</table>

design and fabrication of an optical fiber made of water

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with solid-cladding devices, capillary oscillations are not restricted, allowing the fiber walls to move and vibrate. The fiber is constructed by a high direct current (DC) voltage of several thousand volts (kV) between two water reservoirs that creates a floating water thread, known as a water bridge. Through the choice of micropipettes, it is possible to control the maximal diameter and length of the fiber. Optical fiber couplers, at both sides of the bridge, activate it as an optical waveguide, allowing researchers to monitor the water fiber capillary body waves through transmission modulation and, therefore, deducing changes in surface tension.
Co-confining two important wave types, capillary and electromagnetic, opens a new path of research in the interactions between light and liquid-wall devices. Water-walled microdevices are a million times softer than their solid counterparts, accordingly improving the response to minute forces.

The coupling efficiency from a water fiber to a highly multimode fiber can be as high as 54%25,26. The coupling efficiency to a single-mode fiber is up to 12%25,26. Water fibers can be as thin as 1.6 &#181;m in diameter and can have a length of 46 &#181;m (Figure 3)25,26, or they can b...

Watch this Scientific Journal Video about Design and Fabrication of an Optical Fiber Made of Water at JoVE.com

Design and Fabrication of an Optical Fiber Made of Water

This protocol describes the design and manufacture of a water bridge and its activation as a water fiber. The experiment demonstrates that capillary resonances of the water fiber modulate its optical transmission.

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with ...

This method describes the creation of a water bridge and its actuation as a water fiber. The water fiber has no cloudy material and is freely floating in air. The significance of the water fiber is that it co-confines capillary and electromagnetic waves and therefore opens a new playground for research in the interactions between light and liquid well devices.Obtain two PMMA plates to make the reservoirs. Cut each plate to the same size and drill cavities on one side of each in a triangular patterns. The cavities should be seven millimeters in diameter and eight millimeters deep.Glue connector magnets into all of the cavities in each plate. When done, turn the plates over so the magnets are on the bottom. Next, create a pipette clamp for each plate.For a clamp, cut a piece of PMMA and glue two magnets to match the magnets of a reservoir. Make an electrical connector for each plate by wrapping magnets in metallic foil. Thoroughly clean all areas and connectors on each reservoir with alcohol and deionized water.Blow dry the surfaces with nitrogen. Cover the water reservoirs and all clamps with PTFE tape to avoid leaks. Now, mount one reservoir on a five degree of freedom micro positioning stage.For imaging, position the two reservoirs under an optical microscope with a far field objective. Behind each reservoir, set up optical fiber clamps on linear translation stages. Get single-mode fiber for fabricating the tapered coupler.In addition, get the micropipette chosen for the experiment. Use a fiber stripper to expose 10 to 15 millimeters of the bare fiber. After cleaning the fiber's stripped end, thread it through the micropipette.Next, take the fiber to a tapering station. Arrange to pull the fiber segment from both sides at six hundredths of a millimeter per second. While pulling, use a hydrogen flame to taper the fiber below single mode criteria.Turn off the flame, then carefully increase the tension in the fiber until it breaks at its thinnest spot. The slope for use as an optical coupler should be smaller than one over 20. Now, turn to fabricating the fiber lens coupler.This requires 1, 550 animeters single mode fiber with an exposed tip along with a second micropipette chosen for the experiment. Pass the cleaned fiber tip through the micropipette. Next, take the fiber to an electric fusion splicer and place the exposed tip inside.Heat the tip until the glass fiber end becomes liquid. Stop after the glass becomes liquid and forms a rounded shape, the glass fiber lens. At this point, assemble the elements of the apparatus.Start with the reservoir on the positioning stage. Position the micropipette with the 1, 550 animeter fiber so one end is in the reservoir region. Secure it with the PMMA clamp.Ensure that the glass fiber lens is under the microscope. Have the other end of the fiber coupled to a power meter and clamped to a linear translation stage. On the other reservoir, clamp the micropipette and tapered fiber in place with the tapered end under the microscope.Its other end should also be clamped to a linear translation stage and coupled to a 780 nanometer continuous wave laser. Now, fill the reservoirs with deionized water. Each reservoir can hold 100 to 300 microliters.Ensure that there are no bubbles in either of the micropipettes. Adjust the micro positioner to establish a fluidic contact between the micropipettes. This image provides an example of fluidic contact.Continue once contact is confirmed. Further adjust the fibers and micro positioner to achieve transmission of laser light. Do this by inserting the fiber couplers into the water fiber.Aligning the system is not as straightforward as it seems. The water fiber and the couplers are not attracted to each other. To achieve good transmission, one needs to push the couplers forcefully into the water fiber.For electrical connections, place the magnetic connectors on each reservoir. They should be magnetically secured and their foil should have crocodile clamps in place. Use electrical cables to connect the clamps to the terminals of a high voltage source.Once everything is ready, slowly increase the voltage. Adjust the micro positioning stage to slowly increase the distance between the micropipettes. Next, take a power measurement to determine the coupling efficiency, then disconnect the power meter.In its place, connect a photo receiver to the output fiber coupler. Display the output of the photo receiver on an oscilloscope. Record time trace measurements of the transmitted light which represents the capillary water fiber oscillations.Use the top view microscope setup to characterize the geometry of the water fiber. Fibers produced with this method can be as long as one millimeter with a diameter of about 40 micrometers. They can also be about 50 micrometers in length with a diameter of about 1.5 micrometers.This fluorescent dye measurement confirms light transmission through the water fiber volume. Another measurement demonstrates surface scattering due to capillary waves at the water fiber liquid phase boundary. The implications of this technique extend toward multi wave detectors.Current detectors utilize one kind of wave. The water fiber hosts three different kinds of waves, capillary, acoustic, and optical, which can exchange energy and interrogate each other. While attempting this procedure, it is important to remember to pay close attention to the fabrication of the optical couplers.Also, running the experiment involves a risk of breaking or damaging the tapered fiber couplers, mechanically or through an electric arch. Generally, individuals new to this method will struggle because high electrical water resistivity is crucial for this experiment. Even small amounts of ions in the liquid will cause the water bridge to collapse.Don't forget that working with high voltages and high powered laser light can be extremely hazardous and precautions, such as proper electrical grounding and eye protection, should always be taken while performing this procedure.

design-and-fabrication-of-an-optical-fiber-made-of-water

Research

JoVE Journal

Engineering

Fabricating Metamaterials Using the Fiber Drawing Method

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe their electromagnetic properties to the structure of their constituents, instead of the atoms that compose them. For example, sub-wavelength metal wires can be arranged to possess an effective electric permittivity that is either positive or negative at a given frequency, in contrast to the metals themselves 2. This unprecedented control over the behaviour of light can potentially lead to a number of novel devices, such as invisibility cloaks 3, negative refractive index materials 4, and lenses that resolve objects below the diffraction limit 5. However, metamaterials operating at optical, mid-infrared and terahertz frequencies are conventionally made using nano- and micro-fabrication techniques that are expensive and produce samples that are at most a few centimetres in size 6-7. Here we present a fabrication method to produce hundreds of meters of metal wire metamaterials in fiber form, which exhibit a terahertz plasmonic response 8. We combine the stack-and-draw technique used to produce microstructured polymer optical fiber 9 with the Taylor-wire process 10, using indium wires inside polymethylmethacrylate (PMMA) tubes. PMMA is chosen because it is an easy to handle, drawable dielectric with suitable optical properties in the terahertz region; indium because it has a melting temperature of 156.6 &deg;C which is appropriate for codrawing with PMMA. We include an indium wire of 1 mm diameter and 99.99% purity in a PMMA tube with 1 mm inner diameter (ID) and 12 mm outside diameter (OD) which is sealed at one end. The tube is evacuated and drawn down to an outer diameter of 1.2 mm. The resulting fiber is then cut into smaller pieces, and stacked into a larger PMMA tube. This stack is sealed at one end and fed into a furnace while being rapidly drawn, reducing the diameter of the structure by a factor of 10, and increasing the length by a factor of 100. Such fibers possess features on the micro- and nano- scale, are inherently flexible, mass-producible, and can be woven to exhibit electromagnetic properties that are not found in nature. They represent a promising platform for a number of novel devices from terahertz to optical frequencies, such as invisible fibers, woven negative refractive index cloths, and super-resolving lenses.

Metamaterials at terahertz frequencies offer unique opportunities, but are challenging to fabricate in bulk. We adapt the fabrication procedure for microstructured polymer optical fibers to inexpensively fabricate metamaterials potentially on an industrial scale. We produce polymethylmethacrylate fibers containing ~10 &mu;m diameter indium wires separated by ~100 &mu;m, which exhibit a terahertz plasmonic response.

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe ...

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on photoconduction, which has been one of the most commonly used techniques for terahertz generation 1-8. Terahertz generation in a photoconductive emitter is achieved by pumping an ultrafast photoconductor with a pulsed or heterodyned laser illumination. The induced photocurrent, which follows the envelope of the pump laser, is routed to a terahertz radiating antenna connected to the photoconductor contact electrodes to generate terahertz radiation. Although the quantum efficiency of a photoconductive emitter can theoretically reach 100%, the relatively long transport path lengths of photo-generated carriers to the contact electrodes of conventional photoconductors have severely limited their quantum efficiency. Additionally, the carrier screening effect and thermal breakdown strictly limit the maximum output power of conventional photoconductive terahertz sources. To address the quantum efficiency limitations of conventional photoconductive terahertz emitters, we have developed a new photoconductive emitter concept which incorporates a plasmonic contact electrode configuration to offer high quantum-efficiency and ultrafast operation simultaneously. By using nano-scale plasmonic contact electrodes, we significantly reduce the average photo-generated carrier transport path to photoconductor contact electrodes compared to conventional photoconductors 9. Our method also allows increasing photoconductor active area without a considerable increase in the capacitive loading to the antenna, boosting the maximum terahertz radiation power by preventing the carrier screening effect and thermal breakdown at high optical pump powers. By incorporating plasmonic contact electrodes, we demonstrate enhancing the optical-to-terahertz power conversion efficiency of a conventional photoconductive terahertz emitter by a factor of 50 10.

We describe methods for the design, fabrication, and experimental characterization of plasmonic photoconductive emitters, which offer two orders of magnitude higher terahertz power levels compared to conventional photoconductive emitters.

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on ...

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 &mu;m. Initially, each strand is 200 &mu;m in diameter and 8-inches long. During the mixing process of the original fiber strands, the fibers cross over each other; however, a large draw ratio guarantees that the refractive index profile is invariant along the length of the fiber for several tens of centimeters. The large refractive index difference of 0.1 between the disordered sites results in a small localized beam radius that is comparable to the beam radius of conventional optical fibers. The input light is launched from a standard single mode optical fiber using the butt-coupling method and the near-field output beam from the disordered fiber is imaged using a 40X objective and a CCD camera. The output beam diameter agrees well with the expected results from the numerical simulations. The disordered optical fiber presented in this work is the first device-level implementation of 2D Anderson localization, and can potentially be used for image transport and short-haul optical communication systems.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. This microstructured fiber can transport a small localized beam with a radius that is comparable to the beam radius of conventional optical fibers.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed ...

Patterning via Optical Saturable Transitions - Fabrication and Characterization

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical Saturable Transitions (POST). In this technique the chemical properties of organic photochromic molecules that undergo single-photon reactions are exploited, enabling rapid top-down nanopatterning over large areas at low light intensities, thereby, allowing for the circumvention of the far-field diffraction barrier.4 Simple, cost-effective, high throughput and resolution alternatives to nanopatterning are being explored, such as, two-photon polymerization5,6, beam pen lithography (BPL)7, scanning electron beam lithography (SEBL), and focused ion beam (FIB) patterning. However, multi-photon approaches require high light intensities, which limit their potential for high throughput and offer low image contrast. Although, electron and ion beam lithographic processes offer increased resolution, the serial nature of the process is limited to slow writing speeds, which also prevents patterning of features over large areas. Beam-pen lithography is an approach towards parallel near-field optical lithography. However, the gap between the source of the beam and the surface of the photoresist needs to be controlled extremely precisely for good pattern uniformity and this is very challenging to accomplish for large arrays of beams. Patterning via Optical Saturable Transitions (POST) is an alternative optical nanopatterning technique for patterning sub-wavelength features1-3. Since this technique uses single photons instead of electrons, it is extremely fast and does not require high light intensities1-3, opening the door to massive parallelization.

We report that the diffraction limit of conventional optical lithography can be overcome by exploiting the transitions of organic photochromic derivatives induced by their photoisomerization at low light intensities.1-3 This paper outlines our fabrication technique and two locking mechanisms, namely: dissolution of one photoisomer and electrochemical oxidation.

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical ...

Fabrication and Operation of a Nano-Optical Conveyor Belt

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological and physical sciences over the past few decades. The progress made in this field invites further study of even smaller systems and at a larger scale, with tools that could be distributed more easily and made more widely available. Unfortunately, the fundamental laws of diffraction limit the minimum size of the focal spot of a laser beam, which makes particles smaller than a half-wavelength in diameter hard to trap and generally prevents an operator from discriminating between particles which are closer together than one half-wavelength. This precludes the optical manipulation of many closely-spaced nanoparticles and&#160;limits the&#160;resolution of optical-mechanical systems. Furthermore, manipulation using focused beams requires beam-forming or steering optics, which can be very bulky and expensive. To address these limitations in the system scalability of conventional optical trapping our lab has devised an alternative technique which utilizes near-field optics to move particles across a chip. Instead of focusing laser beams in the far-field, the optical near field of plasmonic resonators produces the necessary local optical intensity enhancement to overcome the restrictions of diffraction and manipulate particles at higher resolution. Closely-spaced resonators produce strong optical traps which can be addressed to mediate the hand-off of particles from one to the next in a conveyor-belt-like fashion. Here, we describe how to design and produce a conveyor belt using a gold surface patterned with plasmonic C-shaped resonators and how to operate it with polarized laser light to achieve super-resolution nanoparticle manipulation and transport. The nano-optical conveyor belt chip can be produced using lithography techniques and easily packaged and distributed.

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Fabrication of an Optical Cell Dryer for the Spectroscopic Analysis Cells

Optical cells, which are experimental instruments, are small, square tubes sealed on one side. A sample is placed in this tube, and a measurement is performed with a spectroscope. The materials used for optical cells generally include quartz glass or plastic, but expensive quartz glass is reused by removing substances, other than liquids, to be analyzed that adhere to the interior of the container. In such a case, the optical cells are washed with water or ethanol and dried. Then, the next sample is added and measured. Optical cells are dried naturally or with a manual hairdryer. However, drying takes time, which makes it one of the factors that increase the experiment time. In this study, the objective is to drastically reduce the drying time with a dedicated automatic dryer that can dry multiple optical cells at once. To realize this, a circuit was designed for a microcomputer, and the hardware using it was independently designed and manufactured.

A protocol for fabricating a device for simultaneously drying multiple optical cells is presented.

Optical cells, which are experimental instruments, are small, square tubes sealed on one side. A sample is placed in this tube, and a measurement is ...

Low-cost Custom Fabrication and Mode-locked Operation of an All-normal-dispersion Femtosecond Fiber Laser for Multiphoton Microscopy

A protocol is presented to build a custom low-cost yet high-performance femtosecond (fs) fiber laser. This all-normal-dispersion (ANDi) ytterbium-doped fiber laser is built completely using commercially available parts, including $8,000 in fiber optic and pump laser components, plus $4,800 in standard optical components and extra-cavity accessories. Researchers new to fiber optic device fabrication may also consider investing in basic fiber splicing and laser pulse characterization equipment (~$63,000). Important for optimal laser operation, methods to verify true versus apparent (partial or noise-like) mode-locked performance are presented. This system achieves 70 fs pulse duration with a center wavelength of approximately 1,070 nm and a pulse repetition rate of 31 MHz. This fiber laser exhibits the peak performance that may be obtained for an easily assembled fiber laser system, which makes this design ideal for research laboratories aiming to develop compact and portable fs laser technologies that enable new implementations of clinical multiphoton microscopy and fs surgery.

A method is presented to build a custom low-cost, mode-locked femtosecond fiber laser for potential applications in multiphoton microscopy, endoscopy, and photomedicine. This laser is built using commercially available parts and basic splicing techniques.

A protocol is presented to build a custom low-cost yet high-performance femtosecond (fs) fiber laser. This all-normal-dispersion (ANDi) ytterbium-doped ...

Fabrication and Design of Wood-Based High-Performance Composites

Delignified densified wood is a new promising and sustainable material that possesses the potential to replace synthetic materials, such as glass fiber reinforced composites, due to its excellent mechanical properties. Delignified wood, however, is rather fragile in a wet state, which makes handling and shaping challenging. Here we present two fabrication processes, closed-mold densification and vacuum densification, to produce high-performance cellulose composites based on delignified wood, including an assessment of their advantages and limitations. Further, we suggest strategies for how the composites can be re-used or decomposed at the end-of-life cycle. Closed-mold densification has the advantage that no elaborate lab equipment is needed. Simple screw clamps or a press can be used for densification. We recommend this method for small parts with simple geometries and large radii of curvature. Vacuum densification in an open-mold process is suitable for larger objects and complex geometries, including small radii of curvature. Compared to the closed-mold process, the open-mold vacuum approach only needs the manufacture of a single mold cavity.

Delignified densified wood represents a new promising lightweight, high-performance and bio-based material with great potential to partially substitute natural fiber reinforced- or glass fiber reinforced composites in the future. We here present two versatile fabrication routes and demonstrate the possibility to create complex composite parts.

Delignified densified wood is a new promising and sustainable material that possesses the potential to replace synthetic materials, such as glass fiber ...

Measurement of Chladni Mode Shapes with an Optical Lever Method

Quantitatively determining the Chladni pattern of an elastic plate is of great interest in both physical science and engineering applications. In this paper, a method of measuring mode shapes of a vibrating plate based on an optical lever method is proposed. Three circular acrylic plates were employed in the measurement under different center harmonic excitations. Different from a traditional method, only an ordinary laser pen and a light screen made of ground glass are employed in this novel approach. The approach is as follows: the laser pen projects a beam to the vibrating plate perpendicularly, and then the beam is reflected to the light screen in the distance, on which a line segment made of the reflected spot is formed. Due to the principle of vision persistence, the light spot could be read as a bright straight line. The relationship between the slope of the mode shape, length of the light spot and the distance of the vibrating plate and the light screen can be obtained with algebraic operations. Then the mode shape can be determined by integrating the slope distribution with suitable boundary conditions. The full-field mode shapes of Chladni plate could also be determined further in such a simple way.

A simple method of measuring the Chladni mode shape on an elastic plate by the principle of an optical lever is proposed.

Quantitatively determining the Chladni pattern of an elastic plate is of great interest in both physical science and engineering applications. In this ...