Optical dynamic memory based on an integrated active ring resonator.

All-optical computing has been considered a solution for future computers to overcome the speed bottleneck encountered by the current electronic computers. High-speed optical memory is one of the key building blocks in realizing all-optical computing. In this Letter, we demonstrate an optical dynamic memory based on an amplified high Q-factor ring resonator that has the capability to achieve an infinite memory time. The optical memory uses an external pulse train to refresh the resonator, an operation in analogy to an electronic dynamic random-access memory widely used in modern computers, but at a speed that can be orders of magnitude faster. In our demonstration, a writing speed of 2.5 GHz is achieved with instant reading capability. The maximum writing speed can be as fast as 27.3 GHz if a shorter pulse is used.

An integrated parity-time symmetric wavelength-tunable single-mode microring laser.

Mode control in a laser cavity is critical for a stable single-mode operation of a ring laser. In this study we propose and experimentally demonstrate an electrically pumped parity-time (PT)-symmetric microring laser with precise mode control, to achieve wavelength-tunable single-mode lasing with an improved mode suppression ratio. The proposed PT-symmetric laser is implemented based on a photonic integrated circuit consisting of two mutually coupled active microring resonators. By incorporating multiple semiconductor optical amplifiers in the microring resonators, the PT-symmetry condition can be achieved by a precise manipulation of the interplay between the gain and loss in the two microring resonators, and the incorporation of phase modulators in the microring resonators enables continuous wavelength tuning. Single-mode lasing at 1,554.148 nm with a sidemode suppression ratio exceeding 36 dB is demonstrated and the lasing wavelength is continuously tunable from 1,553.800 to 1,554.020 nm.

Integrated InP-InGaAsP tunable coupled ring optical bandpass filters with zero insertion loss.

Second and third-order monolithically integrated coupled ring bandpass filters are demonstrated in the InP-InGaAsP material system with active semiconductor optical amplifiers (SOAs) and current injection phase modulators (PMs). Such integration achieves a high level of tunability and precise generation of optical filters in the RF domain at telecom wavelengths while simultaneously compensating for device insertion loss. Passband bandwidth tunability of 3.9 GHz to 7.1 GHz and stopband extinction up to 40 dB are shown for third-order filters. Center frequency tunability over a full free spectral range (FSR) is demonstrated, allowing for the placement of a filter anywhere in the telecom C-band. A Z-transform representation of coupled resonator filters is derived and compared with experimental results. A theoretical description of filter tunability is presented.