Storing and delaying optical signals plays a crucial role in data centers, phased array antennas, communication, and future computing architectures. Here, we show a delay scheme based on cascaded Brillouin light storage that achieves multi-stage delay at arbitrary positions within a photonic integrated circuit. Importantly these multiple resonant transfers between the optical and acoustic domain are controlled solely via external optical control pulses, allowing cascading of the delay without the need of aligning multiple structural resonances along the optical circuit. (c) 2018 Optical Society of America.
Storing and delaying optical signals plays a crucial role in data centers, phased array antennas, communication, and future computing architectures. Here, we show a delay scheme based on cascaded Brillouin light storage that achieves multi-stage delay at arbitrary positions within a photonic integrated circuit. Importantly these multiple resonant transfers between the optical and acoustic domain are controlled solely via external optical control pulses, allowing cascading of the delay without the need of aligning multiple structural resonances along the optical circuit. (c) 2018 Optical Society of America.
Storing and delaying optical signals plays a crucial role in data centers, phased array antennas, communication, and future computing architectures. Here, we show a delay scheme based on cascaded Brillouin light storage that achieves multi-stage delay at arbitrary positions within a photonic integrated circuit. Importantly these multiple resonant transfers between the optical and acoustic domain are controlled solely via external optical control pulses, allowing cascading of the delay without the need of aligning multiple structural resonances along the optical circuit.
Stimulated Brillouin scattering describes a way to excite coherent acoustic phonons solely by optically forces in integrated waveguides. It was shown recently that one can use these acoustic phonons to store and delay optical signals [1], [2]. The optical information is resonantly transferred to a coherent acoustic phonon and is then transferred back to the optical domain by a delayed optical retrieval pulse. The storage time, however, is so far limited to a few nanoseconds, determined by the lifetime of the acoustic phonon. A delay of several nanoseconds might be enough for delaying some high speed signals, however increasing the delay time beyond the acoustic lifetime would enable new possibilities for phonon-based on-chip optical signal processing.
Storing and delaying optical signals is key for next generation networks and computing architectures that harness Integrated optics to solve major challenges such as operational bandwidth, capacity and energy efficiency. However, the speed of light, that provides fast data transmission over long distances, becomes a challenge in integrated circuits if one needs to synchronize, reroute, buffer or process data. Therefore, a fast chip-integrated optical buffer is required. Here, we show an approach based on a coherent transfer of information from optical signals to acoustic phonons in a planar integrated circuit. We demonstrate a GHz bandwidth and the compatibility with coherent communication schemes based on amplitude and phase encoding. Furthermore, we show the possibility of advanced on-chip signal processing schemes, such as non-reciprocal light storage.
The importance of optical signal processing techniques is growing rapidly in recent years due to the exponentially increasing demand for bandwidth, capacity and power efficiency in communications and computing. However, due to their bosonic nature photons do not interact with each other, unless there is a nonlinear medium mediating the interaction. One of the strongest nonlinear effects is the interaction of light waves, photons, with sound-waves, acoustic phonons, which is known as stimulated Brillouin scattering (SBS). This thesis experimentally investigates SBS in photonic chips. It is shown in this thesis that the fundamental interaction strength between light and sound waves can be tailored by using one-dimensional photonic bandgap structures, completely suppressing the effect or alternatively enhancing the interaction to form phase-locked Brillouin frequency combs. It was shown furthermore that efficiently generating SBS on-chip enables the generation of stable RF signals that are widely tunable in frequency. Finally, it is shown in this thesis that SBS enables the storage of light signals on a chip, one of the holy grails of all-optical signal processing. Delaying optical signals is of key importance in optical networks to enable synchronization, buffering, and rerouting. SBS enables large delays by resonantly transferring an optical signal to an acoustic wave, that travels five orders of magnitude slower and retrieving it after a certain storage time. It is demonstrated in this thesis that a Brillouin-based memory (BBM) technique allows storing amplitude and phase of optical data pulses and operate at multiple wavelengths with minimal cross-talk. Replenishing of the acoustic wave to overcome storage time limitations imposed by the lifetime of the acoustic wave as well as non-reciprocal light storage is also shown.
In order to deliberately control the flow of optically encoded information, optical storage is an indispensable tool, but it must maintain all the advantages of optics, such as i.e. the coherence, the bandwidth and capacity. An elegant approach to this problem is to coherently transfer the information from optical to acoustic waves via an opto-mechanical nonlinearity, such as stimulated Brillouin scattering (SBS). The basic concept was first demonstrated in highly nonlinear fiber by Zhu et al. [1]. Recently, we experimentally demonstrated the coherence of this memory concept by encoding different amplitude and phase levels in an integrated photonic circuit [2] and the compatibility with wavelength division multiplexing [3]. This concept is based on a straight waveguide without the need of a structural resonance as an opto-mechanical resonator or a photonic crystal cavity. Therefore, the memory operation can be arbitrarily positioned on the photonic chip and can even be repeated and cascaded several times, via external control light pulses.
Abstract Storing or delaying optical signals is of key interest for fundamental research and applications in radar, microwave signal processing, quantum information as well as optical communication systems. Delay systems based on stimulated Brillouin scattering (SBS), a coherent interaction between optical and acoustic waves can be implemented in optical fiber or chip-scale platforms, operate at room temperature and can be fully controlled via the optical pump wave. In this article, we review delay and storage techniques based on SBS. We present SBS slow-light, fiber delay lines based on Brillouin dynamic gratings, Brillouin quasi-light storage and Brillouin-based light storage via photon-phonon conversion and compare their performance. In this process, we also include an overview of different platforms used for Brillouin light storage and delay schemes, such as optical fiber, planar soft-glass waveguides, and silica fiber-tip resonators.