摘要:
A method and system of operating a variable optical attenuator to provide a required total attenuation in a planar lightwave circuit. The method comprises providing a first Mach-Zehnder interferometer having a first and a second arm carrying signals in an arbitrary polarization state, providing a second Mach-Zehnder interferometer having a third and a fourth arm carrying signals in an arbitrary polarization state, the second Mach-Zehnder interferometer concatenated in tandem with the first Mach-Zehnder interferometer, and cooperatively operating the concatenated first and second Mach-Zehnder interferometers to obtain the required total attenuation and an effectively nil polarization dependent loss.
摘要:
Broadband optical switches based on adiabatic couplers having a pair of asymmetric waveguides with variable curvature sections include in a 2×2 configuration based on a Mach-Zehnder interferometer two such adiabatic couplers, and in a 1×2 or 2×1 configuration an adiabatic coupler and an Y-splitter. Each adiabatic coupler includes two waveguide branches of different but constant widths having curved sections with varying radii, separated over a coupling length by a changing spacing therebetween and blending in an asymmetric intersection area, and two symmetric branches. In the 2×2 switch, the two adiabatic couplers face each other with their respective symmetric branches, and are connected by the two identical arms along a main propagation axis in a mirror image. The utilization of the variable curvature adiabatic couplers in silica MZI switches on a silicon substrate provides switches with an exceptional broadband range (1.2-1.7 μm), very high extinction ratios (>35 dB), low fabrication sensitivity and polarization independent operation. The switches are significantly smaller than known broadband switches, have significantly smaller excess loss, faster switching time and low power consumption.
摘要:
A laser assembly and a method for controlling light output thereof are presented. The laser assembly comprises a semiconductor laser diode having an active region and its associated electric current driver. The electric current driver is controllably operated to excite said active region to induce a certain electric current profile therethrough. The electric current profile corresponds to a desired emission profile from the laser assembly and a desired over heating profile of the active region of the laser diode, while maintaining predetermined temperature range of said active region of the semiconductor laser diode.