Effect of Ring Resonator Waveguide Loss on SFDR Performance of Highly Linear Optical Modulators Under Suboctave Operation

We investigate the effect of ring resonator (RR) waveguide loss on the spurious-free-dynamic-range (SFDR) performance of two types of highly linear, resonator-enhanced optical modulators, namely, 1) the Resonator-Assisted Mach-Zehnder Interferometer (RAMZI) modulator, and 2) the Interferometric Modulator with Phase-modulating And Cavity-modulating Components (IMPACC). We show that the respective SFDR values of both traveling-wave RAMZI and traveling-wave IMPACC degrade by as much as 20 dB from their peak values when the RR waveguide loss increases by 20%. However, unlike RAMZI, the IMPACC design allows for SFDR compensation (from 114 to 132 dB) by simply adjusting one of its externally accessible parameter controls-the radio-frequency power split ratio, under suboctave operation. This unique feature of IMPACC provides optimum performance, adds greater design flexibility, and increases manufacturing tolerance.