le the development of a range of passive glass components such as couplers, split- ters, waveguides, WDMs, mirrors, gratings, and lenses. 10 The five existing conventional glass fabrication methods all suffer drawbacks when com- pared with sol-gel techniques. These conventional methods are sputtering, thermal oxidation and nitridation, chemical vapor deposition (CVD), plasma-enhanced low-temperature chemical vapor deposition (PECVD), and flame hydrolysis deposition (FHD). Some vendors (such as PIRI, Siemens, and Kymata) use the FHD method. With this method, a hydrogen- oxygen nozzle flame burns gasses; the combustion of these gases produces a glass soot that is melted at -1,000°C. This process takes more than six hours and is repeated three times. The second coating step is followed by a series of coating and vacuum-etching steps. The PHASIC method, on the other hand, uses an HSGG; the components are made by spin- or dip- coating fluids at 100 to 200°C. Next, the devices are created by photolitho- graphy directly in the HSGG, avoiding vacuum film deposition and repetitive steps. One issue with passive devices, however, is power. After a few nodes, the original power is reduced appreciably; however, this issue is manageable in a metro access environment with relatively small (in diam- eter) rings. The phased-array technology is similar in concept to the passive optical network (PON) systems that are being discussed by the industry for residential use. Dense Wavelength Division Multiplexing (DWDM) Systems The best market research available indicates that today there are 21,000 office buildings in the United States on fiber, and the number is expected to increase to about 32,000 office buildings by 2005. 11 As an average, consider- ing 60 major cities in the United States, there were 350 office buildings on fiber for each city in 2001 and will be 530 office buildings on fiber for each city in 2005. Further, assuming access rings with 16 buildings in each ring, this implies that as an average, there were 22 metro acc