Laser inscribed waveguide optical isolators in iron-doped lithium niobate.

There is a growing need for optical isolators that do not require a magnetic field, especially for uses such as on-chip optical devices and cold atom physics. As one approach, we propose using waveguides in photorefractive materials, such as Fe:LiNbO3, as optical isolator devices due to their unique asymmetric transmission properties that allow low loss transmission in one crystal orientation and attenuation in the flipped orientation. We utilize ultrafast laser inscription to fabricate photorefractive depressed cladding waveguides in Fe:LiNbO3 along the crystal c axis to demonstrate the operation of Fe:LiNbO3 waveguide optical isolators. We show the ability to write transmission and reflection gratings into these waveguides that provide an isolation ratio of approximately 5000:1 per cm of path length.

Continuous wave Fe2+:ZnSe mid-IR optical fiber lasers.

Today fiber lasers in the visible to near-infrared region of the spectrum are well known, however mid-infrared fiber lasers have only recently approached the same commercial availability and power output. There has been a push to fabricate optical fiber lasers out of crystalline materials which have superior mid-IR performance and the ability to directly generate mid-IR light. However, these materials cannot currently be fabricated into an optical fiber via traditional means. We have used high pressure chemical vapor deposition (HPCVD) to deposit Fe2+:ZnSe into a silica optical fiber template. These deposited structures have been found to exhibit laser threshold behavior and emit CW mid-IR laser light with a central wavelength of 4.12 µm. This is the first reported solid state fiber laser with direct laser emission generated beyond 4 µm and represents a new frontier of possibility in mid-IR laser development.

Analysis of Popcorn (Zea mays L. var. everta) for Antioxidant Capacity and Total Phenolic Content.

Popcorn, one of the most popular snack foods in the world, is known for being a high fiber, healthy food. Our research has found that commercial popcorn also contains significant amounts of the class of antioxidants known as phenolic acids. The total antioxidant power of raw and popped popcorn extract has been quantified using the Folin-Ciocalteu and FRAP assays. The polyphenols were found exclusively in the pericarp of the kernel completely bound to the oligosaccharide fiber matrix. An in vitro digestion study was also performed to predict the phenolic acids' bioavailability. On average, nine commercial popcorn samples contain 5.93 ± 0.92 mg/g of total polyphenols after alkaline hydrolysis and 2.66 ± 0.15 mg/g after in vitro digestion as measured by the Folin-Ciocalteu assay. Furthermore, the popping process was found not to significantly decrease the antioxidant capacity. These results indicate that a considerable amount of the bound polyphenols are bioaccessible. Due to the high levels of bioaccessible polyphenols, popcorn may be a significant source of dietary polyphenol antioxidants.

Effect of thermal processing on free and total phenolics in nine varieties of common beans.

Though much attention has been devoted to phenolics in beans, to our knowledge no studies have been done to determine the effect commercial canning has on these compounds. Free and total phenolic concentration in 18 cultivars of raw beans and 9 cultivars of commercial canned beans was determined. Alkaline hydrolysis was used on samples prior to analysis by Folin-Ciocalteu's reagent (FCR) and ferric-reducing antioxidant power (FRAP). A correction for non-phenolic antioxidants, interferences, was then made. There is a significant difference between the free phenolics of canned and raw beans using FCR (P = 0.006) but not FRAP. There is also a significant difference in the total phenolics of canned and raw beans using FRAP (P = 0.006) but not FCR. When considered on a single serving basis, the amount of phenolics in canned beans is comparable to that provided by raw fruits and vegetables.

Vitamin enhanced waters and polyphenol rich beverages analyzed for antioxidant capacity and antioxidants/calorie.

The purpose of this study was to analyze polyphenol rich beverages (vitamin enhanced waters (VEWs), fruit juices and berry juices) to determine free polyphenol concentrations and free polyphenols per Calorie based on a serving size. The Folin-Ciocalteu reagent was used in a colorimetric assay based on a catechin standard. Fruit and berry juices contained, on average, more than eight-times the concentration of free polyphenols when compared to VEWs. When Calories per serving were taken into consideration, fruit and berry juices contained more than twice the free polyphenols per Calorie.