As the creators of the SELFOC Lens, NSG Group manufactures and distributes more gradient-index lenses than anyone else in the world. Developed over 30 years ago, the SELFOC Lens has revolutionized the industries of fiber optic communications, medical imaging, and document reproduction by providing a modern alternative to conventional glass optics. The world’s first “self-focusing” lens is now recognized worldwide as a unique, convenient, and economical solution to many optical design challenges. NSG Group and Go!Foton supports this unique product technology with first-rate technical expertise and dependable customer service. For a variety of requirements in countless applications, Go!Foton is focused on your needs.
Go!Foton is the exclusive distributer of SML® products for the optical communication market worldwide. Go!Foton also distributes information device products in North America and Europe.
GRIN and SELFOC
To understand the nature of SELFOC lenses, consider the way a conventional lens works. A conventional glass lens can bend light only at its surfaces. At the interface between air and glass, rays of light will change direction according to the abrupt change in the index of refraction. By carefully controlling the shape and smoothness of the lens surfaces, these rays can be brought to a focus and form an image.
GRIN (GRadient INdex) lenses offer an alternative to the often painstaking craft of polishing curvatures onto glass lenses. By gradually varying the index of refraction within the lens material, light rays can be smoothly and continually redirected towards a point of focus. The internal structure of this index “gradient” can dramatically reduce the need for tightly-controlled surface curvatures and results in a simple, compact lens geometry.
The key to gradient index technology lies in the controlled variation of the refractive index. This is achieved by a high-temperature ion exchange process within the glass host material. The SELFOC lens, manufactured and distributed by NSG America, is produced by a unique ion exchange process that yields stronger index gradients than any other method currently used in production.
With SELFOC technology, optical engineers and researchers have the ability to form a real image on the physical surface of a lens. This creates unique possibilities for coupling light into an optical fiber or relaying an image through an endoscope. The compact, cylindrical geometry makes it possible to put SELFOC lenses into arrays for document scanning or LCD imaging. With a variety of options including AR (Anti-Reflection) coating, metallization, and angled facets, SELFOC lenses may be customized to work for your application.
SELMUX® Solutions Platform
SELMUX is a patented technology that optimizes glass, epoxy and Filter-on-Lens (FOL) technologies to create integrated, Edge WDM couplers and components. This breakthrough advancement eliminates soldering so all SELMUX products are completely lead free and comply with EU directives on the Restriction of Hazardous Substances or RoHS. SELMUX packaging technology now also covers all chip based thin film filter applications including wideband Wavelength Division Multiplexers (WDMs), Coarse WDMs, Dense WDMs, and Gain Flattening Filter (GFF) modules.
The SELMUX packaging platform boasts fewer constituent piece parts, fully compliant (6 of 6) to EU directives on the Restriction of Hazardous Substances (RoHS), qualified to Telcordia GR 1221 standards, and is the only field proven filter based WDM product capable of operating at -40°C to +85°C for rigorous outside plant (OSP) requirements.
The key material ingredient to Go!Foton’s SELMUX Platform is our expertise using FOL technology. FOL coatings are deposited directly on the end face of the SELFOC GRIN lens to create a single integrated, monolithic device, rather than using separate filter substrates. This technique eases alignment, improves reliability and reduces cost by simplifying the manufacturing process. In addition, the integrated FOL process enables a flexible architecture to achieve high isolation and low insertion loss designs which is ideal for broadband applications. By expanding the coverage to include a broad range of chip based filters, the beneficial features of the SELMUX package are now available to the entire field of filter based component applications.
Ultra High Density PEACOC™ Fiber Management Frame
Ultra High Density PEACOC™ Fiber Management Frame for data center and telecom applications. The Go!Foton PEACOC (Patch panel with Enhanced Access for Compact Optical Connectors) Frame boasts easy, tool-less access to 144 standard simplex LC terminations per 1RU for 19″ racks and 162 standard simplex LC terminations per 1RU for 21″ racks, an industry first. Higher density fiber distribution frames allow telecom and data center providers to more efficiently and more cost effectively manage the explosive growth of fiber connections. The PEACOC frame is scalable in increments of 1RU for “pay as you grow” convenience and cost efficiency. A single, fully loaded frame supports over 6000 fiber terminations using standard LC connectors. The port density can be increased even further with the use of smaller form factor connectors, or by using multi-fiber push-on (MPO) connectors. This novel design incorporates Go!Foton’s patent pending PEACOC technology, an innovative, “large finger friendly” fiber jumper management solution that requires no special tools. The Go!Foton PEACOC technology addresses the biggest drawback associated with the use of high density fiber distribution frames today, namely, the difficulty in handling the compact optical connectors to perform fiber jumper management. With PEACOC technology, each individual optical connection can be easily isolated from adjacent optical connections providing a generous region of unobstructed handling space for safe, error free fiber management.
Dr. Yusuke Ota founded Zenko Technologies Inc. in 2002 after retiring from Agere Systems as CMTS. Zenko quickly became an innovative leader in burst-mode technologies for digital communications under Yusuke’s leadership. In 2010, Go!Foton acquired Zenko and Yusuke joined Go!Foton to serve as its CTO.
Prior to founding Zenko, Yusuke had a stellar career of about 30 years with Bell Laboratories, first with AT&T, later Lucent before joining Agere Systems. He initiated the Si molecular beam epitaxy technology and succeeded in growing dislocation-free epitaxial films for the first time in the world. He is also referred to as “Father of Si MBE”. In 1983, he became a member of a task force for developing InP based optoelectronic devices such as InGaAs PIN photodiodes and InGaAsP LED/LD. He received the title of Distinguished Member of Technical Staff (DMTS) in 1983. He invented parallel optical data links and many electronics associated with optical communications. During this period, Yusuke was involved in the material development of optical fibers and study of optical loss. He was also heavily involved the development of alignment technique between optical fiber and active devices. These contributions are really part of the foundation of today’s optical communications industry.
In 1988, he and his colleagues introduced the concept of burst mode optical communication for optical data links. They succeeded to fabricate burst mode receiver IC using Si bipolar IC technology. They also developed a 40-channel parallel optical data link (MODLINK) for future ATM switching system. Even present time, no other parallel optical data link can match with this system. The technology of burst-mode optical communication, which Yusuke invented, actually triggered today’s passive optical networks (PON). Yusuke has been a leader in the field of optical data communications in many aspects.
Yusuke received BS and MS in electronics engineering both from Shizuoka University, Japan, and a Ph.D. degree from the University of Pennsylvania, Philadelphia, PA.
Fiber!FAST™ Indoor Living Unit (ILU) Solutions for FTTH deployment in MDUs
The Fiber!FAST™ Indoor Living Unit (ILU) Solutions. Fiber!FAST™ ILU is an innovative MDU drop cable solution that allows service providers to bring FTTH service to existing MDU living units in a faster and easier fashion. Fiber!FAST™ ILU reduces a carrier’s installation costs and minimizes the disruption and aesthetic objections often associated with retrofitting service cables in existing MDU living units.
Fiber!FAST™ ILU consists of a new 900um drop cable with G657.B3 fiber, the most advanced bend optimized fiber manufactured by Samsung Electronics. The translucent Fiber!FAST™ cable is easily attached to a variety of wall surfaces using simple and discrete plastic clips. Designed and manufactured by Go!Foton, the pathway management toolkit provided with Fiber!FAST™ ILU includes a variety of these clips along with a small tube of specially formulated epoxy which can be applied at discrete points along the cable or smeared like painters caulk, resulting in a truly invisible installation that may be painted by the homeowner if desired. The unique design also provides exceptional mechanical protection when routing the optical drop cable around inside and outside corners. Often missing from other MDU cable solutions, corner protection prevents excessive bending and the formation of stress points on the cable.
Physics of SELFOC
The Gradient Constant
The SELFOC lens utilizes a radial index gradient. The index of refraction is highest in the center of the lens and decreases with radial distance from the axis. The following equation describes the refractive index distribution of a SELFOC lens:
N(r) = N0(1 – √A2/ 2 * r2)
This equation shows that the index falls quadratically as a function of radial distance. The resulting parabolic index distribution has a steepness that is determined by the value of the gradient constant, √A. Although the value of this parameter must be determined through indirect measurement techniques, it is a characterization of the lens’ optical performance. How rapidly rays will converge to a point for any particular wavelength depends on the gradient constant. The dependence of √A and N0, on wavelength is described by the dispersion equations listed at the end of this product guide. Note that different dispersion equations apply to different lens diameters and numerical apertures.
Lens Length & Pitch
In a SELFOC lens, rays follow sinusoidal paths until reaching the back surface of the lens. A light ray that has traversed one pitch has traversed one cycle of the sinusoidal wave that characterizes that lens. Viewed in this way, the pitch is the spatial frequency of the ray trajectory.
The above equation relates the pitch (P) to the mechanical length of the lens (Z) and the gradient constant. The figure below illustrates different ray trajectories for lenses of various pitch. Notice how an image may be formed on the back surface of the lens if the pitch is chosen appropriately.
In contrast to the optics of homogeneous materials, gradient-index optics involve smoothly-varying ray trajectories within the GRIN media. The paraxial (first-order) behavior of these materials is modeled by assuming sinusoidal ray paths within the lens and by allowing the quadratic term in Equation 1 to vanish in the ray-tracing calculations. All of the usual paraxial quantities may be calculated with the help of the ray-trace matrices given at the end of this product guide. The formulae for common paraxial distances have also been tabulated for quick reference.