We present and elaborate the principles of a novel control and calibration (C&C) systematic approach, aiming at feedback stabilization of large scale photonic-integrated circuits (PIC) to their nominal operating points in D-dimensional spaces of tuning parameters, based on refinement of extremum-seeking (ES) realtime optimization techniques. The novel methodology enables, in principle, stabilizing a large number D of tuning degrees of freedom (DOF) of PICs, with just one optical power monitoring (probe) point. The proposed C&C digital controller ports multidimensional ES stabilization concepts to photonics for the first time and further introduces novel improvements to known ES techniques, proposing a new frame-based discrete-multitone method of actuation signals generation and probe signals detection, akin to an orthogonal-frequency-division multiplexing modulation format. Another novel element is that the iterative digital algorithm adaptively selects between gradient-versus Newton-based descent and between various methods of line search. This approach enables real-time application of unconstrained optimization techniques for C&C of photonic circuits with multiple tuning DOFs. The new technique is exemplified by numeric simulations of the stabilization of a Silicon photonic microring modulator with D = 2 tuning DOFs, concurrently tuning both resonant phase and a second coupling phase parameter, optimizing critical coupling into the microring based on observing the optical power at single low-frequency monitoring point.

The state-of-the art for control of microring based devices is tuning just resonant phase. We introduce an extremum-seeking discrete-multitone adaptive controller, concurrently tuning both resonant phase and second coupling phase parameter optimizing microring critical couplin

Coupling modulation in microring resonators substantiates a compact and high bandwidth silicon photonics modulation scheme. In this letter, we present large-signal analysis elucidating that the main drawback of this scheme is the cavity energy decay during analog and digital modulation. Then, we propose a solution, charge-discharge configuration, having two optical inputs to compensate for the power drainage from the ring. This new modulator exhibits RF-bandwidth and extinction ratio not limited by Q-factor with virtually unlimited modulation bandwidth. We emphasize an Orthogonal Frequency-Division Multiplexing (OFDM) modulation format at 50 GHz and show it is feasible on a silicon photonics platform.

No abstract

No abstract