27.08.2014
This item will be sent through the Global Shipping Programme and includes international tracking. Items delivered internationally may be subject to customs processing depending on the item's declared value. Seller has stated it will dispatch the item within 1 working day upon receipt of cleared payment - opens in a new window or tab. Most purchases from business sellers are protected by the Consumer Contract Regulations 2013 which give you the right to cancel the purchase within 14 days after the day you receive the item. Will usually dispatch within 1 working day of receiving cleared payment - opens in a new window or tab. SLA (Stereolitography) 3D printers rely on liquid resin that is being solidified with the help of UV light (Laser, LED or DLP light source), however when the finished print is ready to be removed from the build plate it still needs some more work. We have experimented with different sources of UV light to see if we can easily cure 3D printed parts on our new XYZprinting Nobel 1.0 SLA 3D printer.
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Soft Lithographic Fabrication of Micro Optic and Guided Wave DevicesAngel Flores1 and Michael R. Older african american women hairstyles on - pinterest, Explore sharon sealey's board "older african american women hairstyles" on pinterest, the world's catalog of ideas.
May 15, 2014 by Lisa Leave a Comment Greenway Network this Saturday, May 17, 2014 is kicking off our St.
If you volunteer you will have a chance to win a new 2014 Chevy Sonic donated by Poage Chevrolet! Please help us to inform the public for sound management of our watersheds.
Also, the corn, soy based highly processed foods may be less costly at the store, but in the long run much more expensive for our society. Store-bought pesticides, fertilizers and weed killers contain toxic chemicals that put people and animals at risk — especially children and pets coming into contact with recently treated lawns. When chemicals are washed with rainwater into rivers and streams, and are absorbed into the ground, they can pollute drinking water and other aquifers.
High exposure to chemicals like glyphosate, carbaryl, malathion, and 2,4-D may affect the endocrine system, causing infertility, Parkinson’s disease and Hodgkin’s lymphoma. The Endocrine Society, which studies diseases related to the hormonal system, published a statement in 2009 based on 485 research papersthat showed the potential health effects of endocrine-disrupting chemicals. These studies take decades, Lewis argues, adding, “this means that there are more studies implicating older chemicals, many of which are no longer sold because of known toxicities.” Scientists suspect chemicals still in use are equally harmful. The EPA advises homeowners to wear protective clothing and read warning labels on packages before using pesticides. Some towns across America have started initiatives to cut down on the list of potentially harmful chemicals used by their residents. She points out that developing simpler, more holistic practices can help keep lawns healthy and pollution levels down. Leaving grass clippings on a lawn keeps soil moist for longer periods of time, for example, and letting grass grow to four inches allows roots to grow longer and to absorb more water and nutrients. Experts say those changes have the potential to save time and money, and keep our families — and their drinking water — safe. Food caught between teeth – This is not an emergency but can be a little uncomfortable or embarrassing for the braces-wearing patient. Ligatures Come Off – Tiny rubber bands or small, fine wires, known as ligatures, hold the wire to the bracket.
Irritation of Lips or Cheeks – Sometimes new braces can be irritating to the mouth, especially when the patient is eating. Loose Brackets, Wires or Bands – If the braces have come loose in any way, call the orthodontist to determine appropriate next steps. In case where the light guide tip is more than 10mm away from the surface to be irradiated, light cure for the following time. Estimated delivery dates - opens in a new window or tab include seller's dispatch time, and will depend on postal service selected. If the item comes direct from a manufacturer, it may be delivered in non-retail packaging, such as a plain or unprinted box or plastic bag. Find out more about your rights as a buyer - opens in a new window or tab and exceptions - opens in a new window or tab.
Contact the seller- opens in a new window or tab and request a postage method to your location. Delivery times may vary, especially during peak periods and will depend on when your payment clears - opens in a new window or tab. The first step is to clean it up with the help of stong alcohol that will remove any liquid residues from the resin, then you might need to remove some support material if you needed it. We’ve started with a 3W UV LED lamp from a flashlight, but that was simply not powerful enough an even after an hour the test parts were still not cured well enough. Channel waveguide mode spots of a) single mode and b) multimode waveguides fabricated via VAM.
Waveguide cross-section comparisons single mode waveguides fabricated by VAM technique and by µTM technique. Schematic detailing AWEC optical interconnect technique for card-to-backplane motherboard applications. Diagram depicting AWEC coupling structure and directional coupling between two parallel channel waveguides. When the two waveguides are closely spaced and aligned in the lateral direction, the evanescent fields of the guided modes in the two waveguides overlap causing an alteration of the optical mode and field distributions of the waveguide system. The desire for a well manicured green carpet of grass is in reality is not normal vegetation.
Down that storm water drain, to our streams, our rivers, down to the gulf and into our oceans.
Do not be disappointed if your grass carpet heaven forbid should have dandelions or clover, those bees need that and are they really that bad!
What is now in the works is going back to the old “2,4-D”, it is a herbicide that was used in “agent orange” which was a defoliant dumped on Vietnam years ago.
Despite these potential risks, there are few standards for what sorts of chemicals are acceptable for use on lawns, or in what amounts. Do you think the EPA should set larger-scale safety measures for fertilizers and pesticides that apply to homeowners?
While the Environmental Protection Agency has announced new pesticide safety guidelines to protect farmworkers, no formal set of guidelines exists for homeowners.
In the Patch town of Middletown, Conn., for example, the Project Green Lawn Committee holds workshops and public education events to encourage organic lawn care. Garvey encourages his patients to call the office with any questions regarding orthodontic care. Michael Garvey of Garvey Team Orthodontics has been selected by a vote of his peers to be included in the 2012 database for topDentists. Michael Garveyof Garvey Team Orthodontics did an oral hygiene presentation for career day at Zion Lutheran Elementary School in St.
Garvey is now using a new advanced and improved fluoride sealant when applying brackets to the patients teeth.
Opal Seal is 38% filled with proprietary GI particles and nano fillers that release fluoride during orthodontic treatment. If you reside in an EU member state besides UK, import VAT on this purchase is not recoverable.
You would notice however that the 3D printed part has a bit of rubbery feel and is not yet like a strong plastic, so it needs to be cured with additional UV light to become strong. Then we have moved to UV lamps for checking for counterfeit money, these are usually available with a 4-8W UV lamps and are pretty easy to find, but unfortunately they were still not powerful enough. Micrographs (20? objective) of 35 µm wide master waveguide array (b) and replicated waveguide array (c). Image confirms elimination of polymer background residue and superior device formation through VAM. IntroductionSince the advent of the laser, guided wave and integrated optical devices have attracted significant research interest for use in advanced telecommunication and interconnection systems. Due to the weakly guided nature of the AWEC system (?n = 0.011), coupled mode analysis (Yariv, 1973) can be used to analyze the electromagnetic behavior of the complete structure. In order to impress our neighbors, we as a society are using far too many pesticides and herbicides on our lawns.
The health risks from it’s use have killed many service men and many of the poor people of Vietnam. Charles, MO, orthodontist supplies each patient and school nurses with emergency orthodontic kits and brochures.
Garvey, Thank-you so much for giving up your time to share information about teeth with Zion’s fourth graders.
Charles, MO) and his wife, Lisa, love to go into the local schools and give presentations on braces, Invisalign, teeth straightening techniques, retainers, career paths, and oral hygiene. When Opal Seal has been applied to the tooth surface the use of a UV black light will make the sealant illuminate showing that the resin containing fluoride is present. Garvey has been in practice for 32 years, with a staff of combined years of dental experience of 61 years. After graduating from dental school, orthodontists go on for another two or more years of education just in orthodontics at an accredited orthodontic residency program.
Like these specialists who study their specialty areas after their general medical education, orthodontists devote additional years of study to orthodontics after they graduate from dental school. They each have their uses, but only an orthodontist has the specialized knowledge to identify and plan for all the variables in your mouth. One of the most common and easy ways to do it is to bring out the 3D printed part outside so the sun can shine on it and cure it in a few minutes, however this is not the best way to do it and the sun is not always available when you need it to provide enough UV light. So the next step was a string of UV LED lights where we got about 8W of power per meter and this meant that we needed quite a long strip to get more power out of them and we have moved to looking for alternatives. In this regard, the goal of the coupled-mode theory is to express the electromagnetic fields of the complete structure as a superposition of the unperturbed waveguide electric fields.
Often the chemicals are used incorrectly, the concept is a little stronger concentrations will work better when in fact as mentioned in the below article, we use 10 times more than needed. Genetically modified crops are being pushed onto the public farming community by companies like Monsanto.
Garvey Team Orthodontics are committed to giving their patients a positive and happy experience when they come to our office. Orthodontists are dedicated to helping your teeth and jaws work in union so that you can speak, bite and chew comfortably and effectively.
And like their medical counterparts, orthodontists limit their practices to their specialty area. Orthodontists use their education, experience and expertise to delve deep to discover the root of your orthodontic problem. Orthodontists take your unique needs and wishes into consideration, too, when recommending the right treatment option for you. While various methods can effectively produce guided wave devices, none have been able to match the high-yield, low-cost, mass productivity schemes that define the photolithographic technique in the semiconductor industry. Most importantly, the coupled-mode theory assumes that the waveguide modes remain approximately the same and the coupling interaction modifies the amplitudes of the modes without affecting the modal transverse field distributions or propagation constants of the waveguides. These crops are becoming resistant now to Round-up and Monsanto is creating a new series of genetically modified crops using the old “2,4-D” in combination with Roundup.
Some patients on their first visit are anxious and nervous, but when they leave they are much more at ease and have a cookie in hand and a smile on their face! The goal is met by making sure the separate elements are positioned for optimal performance.


Armed with a diagnosis that takes all factors into account, orthodontists can plan your solution—one that delivers a healthy, attractive smile and a lasting result. Orthodontists have knowledge of the full range of orthodontic appliance “tools.” They know what to use and when to use it because they work with these tools every day. Garvey provides the highest quality of care in achieving beautiful smiles for adults and children while respecting your time, safety, and comfort. It uses four 9W CCFL UV lamps and apparently provides enough UV light in order to cure most 3D printer parts in just a few minutes.
Thus, in the presence of waveguide coupling the modal amplitudes in the two waveguides become functions of the propagation path z. You also taught me some things about teeth that I didn’t know like the shape of the braces are the same shape of the arch. The toxins from commercialized farming and genetically altered seeds after the produce and contaminates the soil and rivers and oceans. It has worked really well with the clear resin prints from the Nobel 1.0 SLA 3D printer and there is enough space to fit inside relatively large objects.
Despite their high yields and exceptional cost performance, photolithography demands the use of a clean-room facility equipped with elaborate semiconductor manufacturing equipment (sputtering machine, e-beam evaporator, mask aligner, reactive-ion etcher, to name a few), leading to undesirable startup costs and prolonged lead times. Garvey, Straight Teeth - See an OrthodontistJune 5, 2012 by admin Leave a Comment Top Dentists – St. Charles MO, Early Orthodontic Care, garvey team, Garvey Team Orthodontics, Oral Hygiene, Orthodontist, Orthodontist St. If you need more space you should be able to pretty easily modify the standard plastic box and make a larger size box with some aluminum foil. As bees forage and pollinate our food they take back the chemicals which bio accumulate in the hives killing entire colonies.
In the ion exchange process, the device substrate is placed in a molten cation bath causing the sodium ions in the glass substrate to exchange with one of the cations (ie., K+, Li+, Cs+). The monoculture of only GM corn and soy bean also result in a major loss of diversity which the bee’s desperately need. The bees will help pollinate the organic produce, also he will in the future sell honey at Triple J Produce and the orthodontic office and Garvey Decor store.
The ion alteration raises the local refractive index of the substrate and creates a waveguiding region in the glass.
Garvey strives to make braces affordable for the whole family with multi-family member discounts, accepting most insurance plans, will match most insurance plans that we are out-of-network, will consider matching competitor fees, Care Credit, and in-house no-interest payment plans.
Garvey, Zion Lutheran Elementary SchoolMay 23, 2012 by admin Leave a Comment Check out our new bracket sealant! Because of their low propagation losses, minimal production costs, and compatibility with optical fibers, the use of ion-exchange waveguides for integrated optical applications has been extensively researched. The honey at stores is often altered with addition of corn sugar and heated which breaks down the organic matrix of the product. On the other hand, waveguides fabricated on glass or semiconductor substrates are normally nonflexible and limited to static planar applications. Later in the season the Buck Wheat the the duck club and organic farm makes a thick dark honey prized by bakers. I liked how you showed us all the different classes of teeth!…   I learned how to brush my teeth, what a Class I bite is, and class II and III bites too…   Thank you for coming to Zion!
More recently, soft-molding replication techniques known as soft lithography are being actively investigated for low-cost, rapid micro-device replication.
To that end, we have been researching diverse soft lithographic techniques for guided wave device fabrication.Soft lithography is a micro-fabrication technique that has been shown to generate high quality micro and nanostructures as small as 10 nm.
Unlike photolithography which is expensive, has little flexibility in material selection, cannot be applied to non-planar surfaces, and provides little control over chemistry of patterned surfaces; soft lithography can circumvent many of these problems.
As a result, soft lithography has generated considerable research interest over the past decade.
Similarly, microfluidic systems with a broad range of chemical and biological applications continue to be an active research area. Microfluidic based devices process or control small amounts of fluids through utilization of channels with micrometer dimensions (Whitesides, 2006). To date, the majority of microfluidic systems have been fabricated using either photolithography, hard replica molding, or more recently, soft lithographic methods (Xia & Whitesides, 1998). Correspondingly, in this chapter we introduce and describe a novel soft lithographic fabrication technique; a vacuum assisted microfluidic (VAM) method that eliminates the polymer background residue inherent in traditional soft molding fabrication techniques. Incorporation of a microfluidic approach with soft lithography allows high-quality guided wave devices to be fabricated rapidly and inexpensively. The VAM technique is used to develop guided wave devices including single mode and multimode channel waveguides, and array waveguide evanescent coupler (AWEC) ribbons for high speed optical interconnections. Garvey!…   I thought the thing was so cool and I want to be an orthodontist when I grow up it is so cool!…   You da mouth!
The fabrication of these devices demonstrates the cost effectiveness and promise of the proposed approach for the development of inexpensive, high-quality, and mass-produced polymer guided wave devices.2. Soft lithographySoft lithography represents a set of high-resolution patterning techniques in which an elastomeric stamp or mold is used for pattern definition. Once the replica stamp is created, multiple copies of the pattern can be defined through straightforward experimental methods. These non-lithographic techniques require minimal monetary investment (clean room not necessary), can be conducted under normal bench top laboratory conditions, and are conceptually simple to fabricate. SAMs are surfaces consisting of a single layer of molecules which are prepared by adding a solution of the molecule to the substrate and washing off the excess mixture.
Depending on the molecular structure and substrate surface, various molecules can be self assembled without the use of molecular beam epitaxy or vapor deposition. 1a, is simple; an elastomeric polydimethylsiloxane (PDMS) stamp is used to transfer molecules of a hexadecanethiol (HDT) ink to the gold surface of the substrate by contact. After printing, any undesired gold material can be etched away to yield the desired pattern.
The technique has been shown to be successful for device fabrication on non-planar surfaces and complex micro patterns.In replica molding (REM), shown in Fig. 1b, an elastomeric mold rather than a rigid mold, is used to create replica patterns (Xia et al., 1997). Here the organic polymer is placed in contact with the PDMS while the mold is being deformed or compressed in a controlled manner.
Deformation of the elastomer provides a method to fabricate structures that would be difficult or unpractical through other procedures. Alike in several ways, µTM is based on the application of a liquid prepolymer against a patterned PDMS mold. After the excess liquid is removed (by scraping or blowing), the filled mold is placed in contact with a substrate, cured and then peeled to generate the patterned microstructure.
Subsequently, soft lithography represents a collection of quick and convenient replication techniques suitable for the definition of both large core (> 100 µm) and nanometer scale devices as well as nanostructures. Master and PDMS stamp fabricationThe key elements in soft lithography are transparent elastomeric PDMS stamps with patterned relief structures on its surface. PDMS is a polymer having the elastic properties of natural rubber that is able to deform under the influence of force and regain its shape when the force is released. This enables PDMS to conform to substrate surfaces over a large area and adapt to form complex patterned structures. Accordingly, our PDMS molds are produced with Sylgard 184 from Dow Corning; a two-part elastomer that is commercially available at low cost. Once a replica stamp is created, multiple copies of the pattern can be defined through straightforward experimental methods, as illustrated in Fig. A master silicon device (channel waveguide array) is developed in SU-8 photoresist through photolithography, as shown in Fig. To begin, SU-8 is spin coated and exposed to UV irradiation through a chromium photomask using a mask aligner. The mask, created via laser-direct writing (Wang & Su, 1998), is a positive replica of the desired channel waveguide arrays.
After post exposure baking and photoresist development, the waveguide array master device is realized. The prepolymer is left to settle for 8 hours to eliminate bubbles (and uniformly settle) and then baked for 1h at 60?C. After thermal curing, the solid prepolymer was peeled off to produce a PDMS replica stamp, as shown in Fig. The replica stamps can be used to create high-fidelity (nanometer scale) copies of the original master pattern. Additionally, the stamps can be reused multiple times (50~100 times) without degradation for mass replication. Microtransfer molding (µTM)Subsequently, initial fabrication of our guided wave devices was based on microtransfer molding.
A schematic description of a standard µTM approach for polymeric waveguide fabrication is presented in Fig. To begin, the device substrate is coated with a low index buffer to act as the cladding layer. Then, a UV curable prepolymer resin is applied onto the PDMS stamp and placed in direct contact with the device substrate. Next, adequate force is uniformly applied to the stamp to assist in the pattern generation. Consequently, UV irradiation through the transparent PDMS mold creates a crosslinking reaction to solidify the waveguide core pattern.
After the resin is cured to a solid, the mold is lifted-off (peeled) to leave a patterned structure on the substrate.
Micrographs (20? objective) of 35 µm wide master waveguide array (b) and replicated waveguide array (c).Microscopic images of the master and replicated channel waveguide arrays are shown in Figs.
We note that because the PDMS mold acts as a secondary master with no influence on the master fabrication, as long as a lower index cladding (or buffer) layer is processed on top of the substrate, a wide array of substrate materials such as glass, silicon wafer, or polymers can be employed.
This will be advantageous as we begin to explore lithe substrates for flexible waveguide performance. Microtransfer molding can generate microstructures over relatively large areas within a short period of time (<1 min).
In addition, once the stamp is developed it can be reused many times for device replication.
Due to its quick curing time and substantial working area the microtransfer molding technique can be used for fast and accurate prototyping. Nevertheless, it is important to mention that the elasticity of PDMS also leads to several drawbacks.
For example, aspect ratios that are too high or too low cause the microstructures in PDMS to deform or distort. Gravity, adhesion and capillary forces exert stress on the elastomeric material causing it to collapse and generate defects in the pattern.
Some of the common defects affecting PDMS generation including feature sagging, ineadequate aspect ratios and surface nonuniformity are a consequence of force applied during the soft molding pattern generation.
Solutions to these and other common defects affecting PDMS replication including polymer residue and structure warping will be explored later.
Polymeric waveguide The polymer material design is critical for the desired high-performance, high-resolution and low-loss guided wave device. The waveguide materials are specifically suited for the fabrication of guided wave devices using soft lithography. The material adheres to the device substrate upon curing without bonding to the PDMS mold during lift-off (peel). Furthermore, we anticipate using both single mode and multimode waveguide structures so the material should be able to create small and large-core devices.


We designed and synthesized two types of photo curable oligomers; epoxy and acrylate oligomers.
The epoxy type oligomer resins were prepared from commercially available dihydroxy (OH) monomers and epichlorohydrin. The acrylate oligomers were synthesized in two steps consisting of an initial reaction between the polyol and diisocyanate monomers, followed by the reaction between the first step byproduct and hydroxy-terminated methacrylate monomers. The prepolymer resins were formulated from the synthetic oligomer, diverse photo curable monomers, additives, and catalytic amounts of photoinitiators. After all the reagents were discharged in a bottle they were dispersed and mixed in an ultrasonic bath for 15~30 min. The formulation study focused on reducing the curing time, shrinkage and determining the proper viscosity.
The curing reactivity and viscosity of the resin can be controlled by addition of multifunctional monomers. Resins for both the core (CO-1) and cladding (C1-1) waveguide materials were synthesized, where the core material was designed with a marginally higher refractive index. The spectrum of both CO-1 and C1-1 (15 micron thick film samples) were measured with a UV-VIS-NIR spectrophotometer.
5, discloses the excellent optical transparencies (> 90%) of the synthesized materials in the visible to near IR communication region. After establishing excellent optical transparency, the refractive indices of the core and cladding materials were carefully regulated.
The refractive index can be explicitly controlled through alteration of the formulation ratio in the fluorinated oligomer portion.
The material developed consists of a controlled mixture of fluorinated epoxy type oligomers, various photo curable additives, and photoinitiators.
The polymer material exhibits excellent broadband (visible to near IR) optical transparency, tunable index control, rapid curing, and light guiding functionality.
Array waveguide device replicationOnce the prepolymer resins were developed, the feasibility of the proposed approach for guided wave device replication was assessed through production of 12 channel waveguide arrays using µTM. The 12-channel waveguide array (each 10 mm long) has dimensions of 35 µm by 35 µm with a 250-micron pitch. Soft lithography was then employed to produce a high-resolution mold of the master pattern.
Following mold generation, several channel waveguide array patterns were produced on a silicon substrate wafer, as shown in Fig. Figure 7.a) Soft lithographic mold of waveguide array master pattern and b) subsequent waveguide arrays fabricated on silicon substrate using soft lithography. We explored the use of different types of soft polymer substrates where the ideal material should be low cost, robust, impact resistant and durable. In addition, properties of high bending radius, UV curing compatibility, excellent thermal resistance, and optical transparency are desired. Polymer sheets of PETG Vivak® co-polyester material were chosen for the waveguide device substrate.
The Vivak® sheet is a low-cost, transparent, thermoplastic sheet widely used for assorted engineering applications. The co-polyester provides superior impact strength, durability and performed well under high-intensity UV illumination. We observed no thermal shrinkage of the co-polyester sheet during UV illumination and the waveguide cladding and core materials bonded and adhered effortlessly to the flexible substrate. Resulting output beam spots emerging directly from the optical waveguide array device are shown in Fig. A VCSEL array source (850 nm wavelength) was used to simultaneously incite all of the array waveguides and light confinement in all channels was achieved.
Mode profile non-uniformity can be attributed in part to the lack of optical preparation (and polishing) on waveguide edge facets.
While soft lithographic fabrication techniques provide a low-cost, mass production solution, our microtransfer molding approach has some drawbacks. Namely, in ?TM the PDMS replica stamp is forcibly pressed against the device substrate, which leads to the creation of a small planar waveguide layer underneath the channel core.
Such undesirable byproduct may hinder waveguide alignment, coupling efficiency and propagation loss performance.
In the ensuing section we introduce a novel soft lithographic fabrication technique that eliminates the required pressing action and waveguide residue layer through a vacuum assisted microfluidic approach.4. Vacuum assisted microfluidic waveguide fabricationCurrently, microfluidic guided wave devices based on liquid core waveguide structures are being investigated.
Microfluidic optical waveguides have been constructed by inserting liquid into a rectangular channel, where light is guided when the index of the liquid exceeds the surrounding medium (Mach et al., 2002).
While these optofluidic waveguides work well in certain biological or analytical instrumentations, their liquid state hinders their applicability in rugged optical communication and photonic applications. Hence, a majority of photonic components manufactured via soft-lithography have been developed through µTM or µCP techniques. In the preceding section, we employed a µTM scheme to develop guided wave devices where multimode channel waveguide arrays were configured.
Such fabrication, where an external force is applied to create the replicated device inevitably leads to the formation of polymer background residue; an unavoidable trait in contact based soft lithography. As the stamp is depressed, the solution on the substrate is forced into the waveguide structure and the excess solution escapes to the edges of the mold. The solution that does not escape forms pockets surrounding the waveguides, resulting in the creation of a planar film layer along the channel waveguide after curing.When the layer is thick enough, it can become an undesirable planar waveguide, greatly affecting the overall waveguide performance or inducing channel-to-channel crosstalk. Even when the layer is thin, it can still affect the channel waveguide confinement resulting in unfavorable waveguide mode profile changes and modal effective index changes. The strong physical contact on the mold can also lead to pattern deformation and warped structures. Hence, the background polymer residue can alter the desired optical performance of the guided wave device.Several possible solutions have been addressed to eliminate polymer background residue, including decreasing the applied force. Nonetheless, it was shown that the force with which the mold is depressed has little effect on the polymer background residue (Paloczi, et al., 2004). In addition, post processing chemical or plasma etching for reducing the residue not only increases manufacturing costs but may affect overall device features such as smoothness and reduction of waveguide thickness. Recently, a new approach for residue reduction was proposed by altering the concentration of the polymer solution (Paloczi, et al., 2004).
Since the residue thickness is dependent on the solution viscosity and density, the background residue can be marginally reduced. However, by thinning the solution, it may reduce the waveguide refractive index resulting in poor waveguide confinement and other device performance including electro-optic effects.
In addition, the thickness of the waveguides is subsequently reduced because there is not enough solid density in the volume of the solution. Towards that end, a vacuum assisted microfluidic (VAM) technique was developed that can circumvent such drawbacks. Although based on microfluid filling of the channel device, the microfluidic resin is cured for the creation of solid core structures. However, before mold replication, posts are placed on the master to generate holes for the microfluidic inlet reservoir and outlet suction, respectively. To further illustrate the concept, a schematic top view of the proposed VAM technique is presented in Fig. A UV curable cladding layer is spin coated and cured upon the desired substrate as seen in Fig.
Then, the PDMS mold and substrate material are placed in conformal contact and a drop of UV curable core resin is placed through the inlet (see Fig. Next, rapid filling of the microfluidic channels is assisted by an aspirator (vacuum of 20 mbar) or syringe attached to the outlet opening.
The moderate suction provided by an aspirator avoids bubble creation or channel deformation that can be normally caused by strong suction devices such as a rotary or diffusion vacuum pumps. A top view picture of the PDMS microchannel structure along with the inlet and outlet orifices of the stamp is presented in Fig.
The ability to fabricate waveguides on rigid substrates (ie., glass, Si) and lithe polymer substrates (co-polyester, polycarbonate, and acrylic) alike, establish the versatility of the VAM approach for fabrication of a wide variety of guided wave devices. Cross sections of identical waveguides fabricated via both µTM and the VAM technique are detailed in Fig. 11 The sample prepared through µTM contains a thin remnant layer (almost 3~5 microns) due to background residue along the channel structure. In contrast the waveguide prepared through the VAM approach was free of polymer background residue.
We also note the improved channel waveguide structure and sidewall edge due to the absence of applied force during the microfluidic fabrication. To further compare both soft lithographic techniques, output mode profile spots of waveguides fabricated by both methods are depicted in the insets of Fig.
The images further attest to the elimination of the planar residue layer and satisfactory guided wave channel structure.
We cite that the fabrication of the PDMS stamp, core and cladding resins, and UV curing procedures are identical to those previously employed in the µTM approach. Hence, the same low-cost, rapid prototyping of µTM were achieved by VAM while eliminating the cumbersome background residue.Optical propagation loss is a vital parameter in communication system design. As such, the optical loss performance of the fabricated waveguide arrays was analyzed via the cutback method.
As expected, improved waveguide formation through use of the microfluidic technique resulted in lower optical loss. Image confirms elimination of polymer background residue and superior device formation through VAM.using identical UV curable resins. A plot of the average transmitted power versus waveguide lengths for both methods is presented in Fig.
The waveguide losses are attributed in part to the unpolished facet edges and optical preparation of the input and output facets should yield much improved loss performance.
Nevertheless, propagation loss reduction (nearly half) is clearly demonstrated, most probably due to the improved waveguide core and reduced defect scattering. Furthermore, low-cost polymer materials exhibiting excellent broadband optical transparency, tunable index control, rapid curing, and light guiding functionality were developed in accordance with the fabrication method. More importantly through the VAM approach, microscopic and SEM analysis depicts improved waveguide structures with no bubbles, defects or planar rib layers. The VAM approach also results in lower propagation losses due to the improved sidewall edges and polymer background residue elimination. VAM fabrication of guided wave devicesIn this section we detail the fabrication of several integrated optic and guided wave devices.
The VAM technique is used to develop single and multi-mode channel waveguides and array waveguide evanescent coupler (AWEC) ribbons for high-speed optical interconnection (Flores, et al., 2008). The fabrication of these devices demonstrates the cost effectiveness and promise of the proposed approach for the development of inexpensive, mass fabrication of polymer guided wave devices. Single mode waveguideWaveguides can be classified according to the total number of guided modes within the steering structure.
Guided wave structures designed to carry only a single allowed propagation parameter are termed single-mode waveguides. Correspondingly, multimode waveguides are designed to accept multiple modes within a guided wave device.



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