We experimentally show an optoacoustic memory based on Brillouin scattering with one order of magnitude higher storage time that retrieves amplitude and phase information after 120ns. We increase the intrinsic phonon lifetime of a highly nonlinear fiber by a factor of six by cooling the fiber down to 4.2K. We demonstrate the performance enhancement of optoacoustic memory by measuring the amplitude and phase information of an initial data pulse and its corresponding retrieved readout pulse using direct and double homodyne detection. Furthermore, we present the influence of different cryogenic temperatures between 4.2K and 20K on the optoacoustic memory and compare the results with continuous-wave measurements. In conclusion, our work can not only accelerate photonic computing but also advance other applications of stimulated Brillouin scattering that require long phonon lifetimes, such as optoacoustic filters in microwave photonics. In addition, the presented long-lasting sound wave optoacoustic memory is compatible with active acoustic refreshment technique potentially leading to all-optical coherent memory beyond 1 μs.
We experimentally show an optoacoustic memory based on Brillouin scattering with one order of magnitude higher storage time that retrieves amplitude and phase information after 120ns. We increase the intrinsic phonon lifetime of a highly nonlinear fiber by a factor of six by cooling the fiber down to 4.2K. We demonstrate the performance enhancement of optoacoustic memory by measuring the amplitude and phase information of an initial data pulse and its corresponding retrieved readout pulse using direct and double homodyne detection. Furthermore, we present the influence of different cryogenic temperatures between 4.2K and 20K on the optoacoustic memory and compare the results with continuous-wave measurements. In conclusion, our work can not only accelerate photonic computing but also advance other applications of stimulated Brillouin scattering that require long phonon lifetimes, such as optoacoustic filters in microwave photonics. In addition, the presented long-lasting sound wave optoacoustic memory is compatible with active acoustic refreshment technique potentially leading to all-optical coherent memory beyond 1 μs.
High Resolution Image Download MS PowerPoint Slide In recent years, remarkable advances in photonic computing have highlighted the need for photonic memory, particularly high-speed and coherent random-access memory. Addressing the ongoing challenge of implementing photonic memories is required to fully harness the potential of photonic computing. A photonic-phononic memory based on stimulated Brillouin scattering is a possible solution, as it coherently transfers optical information into sound waves at high-speed. Such an optoacoustic memory has shown great potential as it fulfills key requirements for high-performance optical random-access memory due to its coherence, on-chip compatibility, frequency selectivity, and high bandwidth. However, the storage time has so far been limited to a few nanoseconds due to the nanosecond decay of the acoustic wave. In this work, we experimentally enhance the intrinsic storage time of an optoacoustic memory by more than 1 order of magnitude and coherently retrieve optical information after a storage time of 123 ns. This is achieved by employing the optoacoustic memory in a highly nonlinear fiber at 4.2 K, increasing the intrinsic phonon lifetime by a factor of 6. We demonstrate the capability of our scheme by measuring the initial and readout optical data pulses with a direct and double homodyne detection scheme. Finally, we analyze the dynamics of the optoacoustic memory at different cryogenic temperatures in the range of 4.2–20 K and compare the findings to continuous wave measurements. The extended storage time is beneficial not only for photonic computing but also for Brillouin applications that require long phonon lifetimes, such as optoacoustic filters, true-time delay networks, and synthesizers in microwave photonics.
Photonic memory is an important building block to delay, route, and buffer optical information, for instance, in optical interconnects or for recurrent optical signal processing. Photonic–phononic memory based on stimulated Brillouin–Mandelstam scattering (SBS) has been demonstrated as a coherent optical storage approach with broad bandwidth, frequency selectivity, and intrinsic nonreciprocity. Here, we experimentally demonstrate the storage of quadrature-phase encoded data at room temperature and at cryogenic temperatures. We store and retrieve the 2-bit states {00, 01, 10, 11} encoded as optical pulses with the phases {0,π2,π,3π2}—a quadrature phase shift keying signal. The 2-bit signals are retrieved from the acoustic domain with a global phase rotation of π, which is inherent in the process due to SBS. We also demonstrate full phase control over the retrieved data based on two different handles: by detuning slightly from the SBS resonance or by changing the storage time in the memory scheme, we can cover the full range [0, 2π). At a cryogenic temperature of 3.9 K, we have increased readout efficiency as well as gained access to longer storage times, which results in a detectable signal at 140 ns. All in all, the work sets the cornerstone for optoacoustic memory schemes with phase-encoded data.
Signal processing based on stimulated Brillouin scattering (SBS) is limited by the narrow linewidth of the optoacoustic response, which confines many Brillouin applications to continuous wave signals or optical pulses longer than several nanoseconds. In this work, we experimentally demonstrate Brillouin interactions at the 150 ps time scale and a delay for a record 15 ns which corresponds to a delay of 100 pulse widths. This breakthrough experimental result was enabled by the high local gain of the chalcogenide waveguides as the optoacoustic interaction length reduces with pulse width. We successfully transfer 150ps-long pulses to traveling acoustic waves within a Brillouin-based memory setup. The information encoded in the optical pulses is stored for 15 ns in the acoustic field. We show the retrieval of eight amplitude levels, multiple consecutive pulses and low distortion in pulse shape. The extension of Brillouin-based storage to the ultra-short pulse regime is an important step for the realisation of practical Brillouin-based delay lines and other optical processing applications.
With the recent developments in photonic computing platforms, the need of novel optical memories becomes increasingly important. Optoacoustic memories have shown great potential due to their quick access time, coherent nature, and broad bandwidth. These continuously tunable memories can be controlled entirely optically, but so far their intrinsic storage time is limited by the acoustic life time to approximately 10 ns. In this work, we experimentally demonstrate a cryogenic optoacoustic memory with an intrinsic storage time beyond 135 ns.
Abstract Signal processing based on stimulated Brillouin scattering (SBS) is limited by the narrow linewidth of the optoacoustic response, which confines many Brillouin applications to continuous wave signals or optical pulses longer than several nanoseconds. In this work, we experimentally demonstrate Brillouin interactions at the 150 ps time scale and a delay for a record 15 ns which corresponds to a delay of 100 pulse widths. This breakthrough experimental result was enabled by the high local gain of the chalcogenide waveguides as the optoacoustic interaction length reduces with pulse width. We successfully transfer 150ps-long pulses to traveling acoustic waves within a Brillouin-based memory setup. The information encoded in the optical pulses is stored for 15 ns in the acoustic field. We show the retrieval of eight amplitude levels, multiple consecutive pulses and low distortion in pulse shape. The extension of Brillouin-based storage to the ultra-short pulse regime is an important step for the realisation of practical Brillouin-based delay lines and other optical processing applications.
Optical and acoustic waves can interact over the nonlinear effect of stimulated Brillouin scattering (SBS), which is a coherent process. By using traveling acoustic waves, we recently showed proof-of-principle experiments of Brillouin-based light storage. The particularity of Brillouin-based light storage is the strict phase-matching condition. This allows for different features: simultaneous storage at multiple wavelengths, cascaded storage at different spatial positions, and nonreciprocal storage with a GHz bandwidth. However, the delay time of this technique has so far been limited to the acoustic lifetime of about 10 ns. In this talk, I will discuss our recent results on coherent photon-phonon interaction. One focus will be on a proof-of-principle experiments on how to reinforce acoustic phonons. This enables us to overcome the obstacle of the limited acoustic lifetime by optically reinforcing the acoustic wave.