Ditherless Optical Modulator Bias Control for Analog Fiber Optic Links with High Dynamic Range

In this SBIR effort, COVEGA Corp. will design and demonstrate a more efficient technology to address challenges associated with bias voltage control of lithium niobate (LN) based modulators using a Mach-Zehnder interferometer (MZI) design. We herein present a solution for elimination of conventional feedback-loop-based bias control, providing three critical advantages for analog RF photonics: (i) elimination of dither-tone-based bias controller side-effects, (ii) enhanced accuracy of MZI phase-lock, and (iii) allowance for MZI operation at any arbitrary phase. In Phase I, COVEGA will meet or exceed the specified system-level requirements by developing a new combination of bias controller which is intimately related to our proposed device architecture. The Phase I project will build on COVEGA’s existing MZI designs, but will incorporate all of our patented device technology, design rules, and processing know-how to achieve low bias swing/drift during changes in environmental conditions. Through the Phase I effort, we intend to prove the feasibility of our proposed design and methodology, resulting in a bench-level prototype of the bias control system as a whole. In Phase II, we intend to further refine the bias control system and fabricate prototype electro-optic modules, integrating both the bias controller and modulator, for DARPA evaluation and deployment.