Low-cost optical sub-assemblies for metro access applications
The fiber optic communications industry is experiencing significant change as datacom 10 Gb/s Ethernet (10 GbE) networks merge with telecom SONET 10G networks in the drive to reach metro access applications. Lower data rate (1G Ethernet, 1G and 2G fiber channel, and SONET OC-48) applications have already merged to some extent as various versions are available within the SFF or SFP standard transceiver form factors. Traditional 10 Gb/s optical subassemblies (OSAs), developed for SONET OC-192 applications, used variations of the expensive butterfly type package. However, smaller form factor modules (such as the XFP that uses SFF optical connectors and LC duplex optical connectors) require much smaller OSAs. To meet the size limitation of packaging 10G OSAs into the XFP transceiver and also meet the 10 GbE market challenge of providing low-cost solutions, new 10 Gb/s OSA components are needed.
Photodiode Packaging Technique Using Ball Lens and Offset Parabolic Mirror
In this paper, we demonstrated the use of a photodiode (PD) packaging technique that employs a catadioptric system. This optical system consisted of two components: a BK7 ball lens with a diameter of 1.5 mm that was soldered with glass on a hermetic cap and a plastic-molded offset parabolic mirror with a radius of 550 mu m and an offset of 550 mu m. The offset parabolic mirror was mounted above a surface-illuminated InGaAs pin PD with a detective area of diameter 20 mum. When an incident pencil of rays were passed through the ball lens and then perpendicularly reflected by the mirror and impinged upon the PD, compact planar assembling became possible for numerous electrical parts on a can-type header for minimizing parasitic impedance due to wire bonds. The optical system provided a high coupling efficiency of 98% between a single-mode fiber and the PD.
Experimental energy barriers to anions transporting through nanofiltration membranes.
Environmentally relevant contaminants fluoride, chloride, nitrate, and nitrite face Arrhenius energy barriers during transport through nanofiltration (NF) membranes. The energy barriers were quantified using crossflow filtration experiments and were in the range of 7-17 kcal·mol(-1), according to ion type and membrane type (Filmtec NF90 and NF270). Fluoride faced a comparatively high energy barrier for both membranes. This can be explained by the strong hydration energy of fluoride rather than other ion properties such as bare ion radius, fully hydrated radius, Stokes radius, diffusion coefficient, or ion charge. The energy barrier for fluoride decreased with pressure, indicating an impact of directional force on energy barriers. The influence of temperature-induced pore radius variability and viscosity on energy barriers was considered. The novel link between energy barriers and ion properties emphasizes the importance of ion hydration and/or partial dehydration mechanisms in determining transport in NF.