Abstract: Monitoring signals associated with operating parameters of an optical transceiver are ascertained by using a comparator arrangement external to a micro-controller unit. Monitoring signals associated with these operating parameter are provided as inputs to a discrete arrangement of comparators and then evaluated against a known reference voltage source. The reference source is swept across a known range of values, and when the output of the comparator changes state, the value of the reference input associated with this transition is defined as the value of the specific monitoring input signal and stored within the proper memory location within the microcontroller portion of the transceiver monitor circuit. The digital output signal of the comparator is applied as an input to the microcontroller, which recognizes this digital signal as defining the specific value of the reference signal to use and equate with the value of the monitored signal.

Abstract: A planar waveguide circuit includes a silica-based planar optical waveguide circuit having a lower cladding, a core and an upper cladding. At least one input waveguide and one output waveguide are each coupled to the optical waveguide circuit. At least one tapered waveguide section is located in the waveguide circuit, which has an upper cladding segment that tapers down to at least the core to define a tapered recess. A filler material having a negative thermo-optic coefficient fills the tapered recess so that the optical waveguide circuit has an optical characteristic with a reduced temperature dependence.