Modulation speed improvement in a Fabry–Perot thermo-optical modulator through a driving signal optimization technique

Abstract

Abstract. A three-power-level method for obtaining efficient thermooptical modulation in an all-silicon waveguide-integrated Fabry-Perot thermo-optic modulator is discussed by means of a thermo-optical analytical model and demonstrated. The thermal system is represented as a two-pole model where, at every time, the temperature in the waveguide core is modified by means of a heater. This temperature is calculated and used in turn for calculating the refractive index. In this way, the impact of the driving signal shape on the device speed performance is assessed. Results clearly indicate that the application of a thermal bias holding the modulator at a higher average temperature with respect to the substrate heat sink allows increasing the modulator speed. An application-specific integrated circuit has been designed and developed in order to test the new modulation logic. The system's electronics is implemented in a 0.8 m, 5 V, CMOS process. The experimental results of this new three-power-level driver method are reported, showing the shortening of the characteristic transient times.

Frequency Response of Thermo-Optic Phase Modulators Based on Fluorinated Polyimide Polymer Waveguide

“…A lumped thermal circuit model was used to analyze the response time of the TOPM. Thermal resistance ( ) and thermal capacitance ( ) of the layers constituting the device were used, then the time constant of the thermal response was obtained [ 23 ]. The lower thermal conductivity and capacitance of the device provides the faster response of the TOPM [ 24 , 25 ].…”

Recent Progress in Silicon Photonics: A Review

“…Owing to the large thermal-optic coefficient of Si (1.86 × 10 −4 /K) [43], thermal modulation, which is based on the temperature dependent of the material refractive, is realizable in Si. Recently, tunable thermaloptic switches and modulators have been demonstrated [44], and the power consumption of this type of modulators is reported being similar to that of plasma dispersion-based modulators [43]. The coefficient can be further increased by using nanostructure Si in silicon-rich silicon oxide (SRSO) thin film [45].…”

“…The coefficient can be further increased by using nanostructure Si in silicon-rich silicon oxide (SRSO) thin film [45]. However, although Della Corte et al has successfully decreased the response time of a thermal-optic modulator to around several microseconds by optimizing the driving signals, this speed is still too slow for the high frequencies required by modern telecommunication applications [44].…”