Optical & Photonics Frequently Asked Questions

1. What is SmartGel?

SmartGel consists of a low viscosity optical fluid and optical thickening agents. When combined, they become a viscoelastic solid with a specific refractive index, high optical clarity, and low absorption loss.


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2. Are there different types of SmartGels?

There are two types of SmartGels: thixotropic and curing. Thixotropic SmartGels are pre-mixed and ready-to-use. When motion is introduced to a thixotropic gel, its viscosity decreases. For example, depressing the plunger of a syringe filled with thixotropic gel makes the gel more fluid-like, allowing it to be pumped into an assembly. Once a thixotropic SmartGel is dispensed, it doesn't migrate out of the assembly. The consistency of thixotropic SmartGels ranges from toothpaste to hard putty.

Curing SmartGels consist of an optical fluid and a soluble optical catalyst that are mixed by the customer. Mixing the two components produces a cured viscoelastic solid. Heat may be used to accelerate the curing process. Both components have a low pre-cure viscosity, which makes it easy to inject them into tight spaces. A reusable two-cartridge dispenser from Nye allows convenient, hand-operated dispensing of small quantities of curing SmartGels.


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3. Why are SmartGels used?

SmartGels improve the efficiency of photonic and telecommunication devices when light inside a device must travel through mated plastic or glass. Air gaps between mated materials cause reflection. Filling the gap with SmartGel virtually eliminates reflection and optimizes light transmission. For example, SmartGel is used to fill the micron-size gap between two glass fibers inside an optical connector, or the gap between a liquid crystal display and the outer lens of a personal digital assistant.


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4. How do SmartGels work?

Air gaps between mated plastic and glass cause reflection because the refractive index of air is lower than the refractive index of the mated materials. Filling the gap with an index-matching SmartGel displaces the air and eliminates the difference in refractive indices that causes reflection and reduces efficiency.


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5. Are SmartGels like optical epoxy?

SmartGels offer advantages over epoxy. Epoxy is rigid, so it can trap stress, fracture, and delaminate. SmartGels absorb shock, minimizing fracture and delaminating. Epoxy can crack when cold and soften when hot. SmartGels are designed to withstand wide temperature excursions (-65°C to ≥200°C), including soldering temperatures during device assembly. Unlike epoxies, SmartGels are non-yellowing under typical conditions and virtually unaffected by x-ray, ultraviolet, or sunlight exposure. Generally, SmartGels are precisely engineered materials. They have extremely low outgassing and volatility characteristics. Optical absorption is typically <0.001% per micron of light path length. They are ultraclean, chemically stable, non-toxic, synthetic materials suitable for designs that require high reliability and long service life.


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6. Why are they called "SmartGels?"

SmartGels "know" how to make the light shine through because they are designed for specific products. The refractive index of a SmartGel is matched to the refractive index of the mated materials (±0.005). A SmartGel's temperature service range, cleanliness levels, and evaporation rate can be matched to product requirements. For thixotropic SmartGels, apparent viscosity can be specified. For curing SmartGels pot life, cure rate, and Shore hardness can be specified. SmartGels can also be formulated to resist water, ionizing radiation, and reactive chemicals.


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7. Where are SmartGels currently used?

SmartGels are now used in fiber optic splices and connectors (Bellcore GR-2919-CORE), high-brightness LEDs, CCD cameras, light therapy technology, and flat panel displays. They are also being tested in a broad range of photonic and telecommunications designs, including personal digital assistants, avionic displays, vision systems, fiber light guides, accent lighting, multiplexors, photodiodes, optical transceivers, optical attenuators, and ultrasonic welding equipment.


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8. How are SmartGels packaged?

SmartGels are typically available in 1cc, 10cc, 30cc, and 55cc syringes; in 20cc and 50cc cartridges; and in 200g and 600g Semco® cartridges.


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9. How do I start experimenting with SmartGels?

Nye's Optical Coupling Kit is a great way to explore how SmartGels can enhance the efficiency of your product. The kit includes two thixotropic SmartGels (NyoGel OC-431A-LVP and NyoGel OC-462) and one curing SmartGel (NyoGel OCK-451).


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