This paper addresses the issue of inserting WDM (wavelength division multiplexing) and amplifier technologies into optical networks from network system architecture and application perspectives. In order to facilitate technology transfer into commercial applications, we need to carefully consider where we can insert the technologies, how we should utilize the technologies, and what are the benefits of employing these technologies. Through years' of investigation and development, taking into considerations of optical network environment, benefits of the technologies and implementation feasibility, we believe that there are three major roles that WDM and amplifier technologies can play in optical networks: point-to-point transmission for capacity expansion, in-fiber out-of-band control for format transparency, and optical routing for network efficiency. In this paper, we will describe each of these roles and their benefits. Progress and results of our related research programs, including optical crossbar switch testbed, will be reported.Although considerable progresses have been made on pushing up the transmission rate through optical fiber to OC-48 and even higher, this still represents only a small fraction of 30 THz (200 mn) bandwidth available in the low-loss wavelength windows of a single-mode optical fiber. Operating over a single wavelength, the increase in transmission rate has to be accompanied by proportional increase of electronic processing speed at the fiber terminating points. Wavelength division multiplexing (WDM) technology is considered an effective approach to exploiting vast optical bandwidth available in the low-loss wavelength range, which divides the optical spectrum into many non-interfering channels, each channel corresponding to different wavelength. 1,2 Tremendous amount of research and development investment has been made on innovative WDM device and amplifier technologies, including various optical network testbeds. Numerous proposals have been made on the utilization of WDM and amplifier technologies in optical networks.3'4'5'6In order to minimize the risk of future investment, we need to carefully evaluate where we can apply the technologies, how we should utilize the technologies, and what are the unique benefits. Our primary considerations include optical network environment, benefits of the technologies, and implementation feasibility. Through extensive research and investigation, we believe that WDM and amplffier technologies can play important roles in: point-to-point transmission for capacity expansion, in-fiber out-of-band control for format transparency, and optical routing for network efficiency. In the following, we will describe each of these roles and their benefits. Progress and results of our related research programs, including optical crossbar switch testbed, are also reported. 78 / SPIE Vol. 2690 0.8194-2064-6/96/$6.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/24/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx