In this paper, we report the use of microelectromechanical system (MEMS) switches in development of a re-configurable optical add/drop multiplexer (ROADM). The implementation of MEMS switches enables fabrication of a highly integrated 16-channel ROADM having compact size, fast re-configuration time, low driving voltage and improved reliability. The dimensions of the die for the 2x2 crossover MEMS switch are 6.5mm x 6.5mm x 1.5mm. The insertion loss of the switch is less than 1 dB. The switching time is less than 3.3ms, and the driving voltage can be as low as 10V. Over 200 million cycles of switching have been achieved. The performance of the MEMS switch and the possibility of implementing the switch in a ROADM will be discussed.
A novel near-infrared diode laser having sensitivity to change of absorption and refractive index at its surface- sensitive region is presented. This semiconductor laser utilizes an AlGaAs single quantum well structure emitting at a wavelength of 950 nm, and its dimensions are 1 mm X 0.5 mm X 0.2 mm. One of the cladding layers is thinned such that the evanescent wave in the quantum well interacts with a surface-sensitive region on the laser. A theoretical model of laser sensitivity toward changes in absorption of a dye- doped polymer coating is formulated. Experimental data using the surface-sensitive diode laser for sensing ammonia and adsorbed monolayers of molecular films are presented. The output power, threshold current and wavelength are shown to be affected by the changes in the adsorbed coating.
An optical fiber fluorescence sensor system capable of compensating fiber bending loss is presented. The system utilized a modulated light-emitting diode and digital-signal processing chips to enhance the measurement of fluorescence signals. A fiber-optic oxygen sensor system suitable for measuring oxygen levels in gas and in aqueous media was developed, and the capability of the system to alleviate fiber bending loss was demonstrated. The signal-to-noise ratio of the system was found to exceed 30 dB using inexpensive components.