Design and Fabrication of an Optical Fiber Made of Water

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.