We demonstrate a platform for phase and amplitude modulation in silicon nitride photonic integrated circuits via piezo-optomechanical coupling using tightly mechanically coupled aluminum nitride actuators. The platform, fabricated in a CMOS foundry, enables scalable active photonic integrated circuits for visible wavelengths, and the piezoelectric actuation functions without performance degradation down to cryogenic temperatures. As an example of the potential of the platform, we demonstrate a compact (~40 μm diameter) silicon nitride ring resonator modulator operating at 780 nm with intrinsic quality factors in excess of 1.5 million, >10 dB change in extinction ratio with 2 V applied, a switching time less than 4 ns, and a switching energy of 0.5 pJ/bit. We characterize the exemplary device at room temperature and 7 K. At 7 K, the device obtains a resistance of approximately 2x10 13 Ohms, allowing it to operate with sub-picowatt electrical power dissipation. We further demonstrate a Mach-Zehnder modulator constructed in the same platform with piezoelectrically tunable phase shifting arms, with 750 ns switching time constant and 20 nW steady-state power dissipation at room temperature.

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Abstract. This paper describes novel time-domain multiplexing techniques that use various resonant cavity configurations for increasing pulse energy extraction per each parallel amplification channel of a coherently combined array. Two different techniques are presented: a so-called N 2 coherent array combining technique, applicable to a periodic pulse train, and a coherent pulse stacking amplification (CPSA) technique, applicable to a pulse burst. The first technique is a coherent combining technique, which achieves simultaneous beam combining and time-domain pulse multiplexing/down-counting using traveling-wave Fabry-Perot type resonators. The second technique is purely a timedomain pulse multiplexing technique, used with either a single amplifier or an amplifier array, which uses traveling-wave Gires-Tourmois type resonators.The importance of these techniques is that they can enable stacking of very large number of pulses, thus increasing effective amplified-pulse duration potentially by 10 2 to 10 3 times, and reducing fiber array size by the corresponding factor. This could lead to very compact coherently combined arrays even for generating very high pulse energies in the range of 1 to 100 J.

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