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We demonstrate a widely tunable and passively mode-locked Tm:Y2O3 ceramic laser in-band pumped by a 1627-nm Raman fiber laser. A tuning range of 318 nm, from 1833 to 2151 nm, is obtained in the continuous-wave regime. The SESAM mode-locked laser produces Fourier-transform-limited pulses as short as 75 fs at ∼ 2.06 µm with an average output power of 0.26 W at 86.3 MHz. For longer pulse durations of 178 fs, an average power of 0.59 W is achieved with a laser efficiency of 29%. This is, to the best of our knowledge, the first mode-locked Tm:Y2O3 laser in the femtosecond regime. The spectroscopic properties and laser performance confirm that Tm:Y2O3 transparent ceramics are a promising gain material for ultrafast lasers at 2 µm.

An increasing number of physical assets, such as academic certificates and credentials, are being represented in the form of digital assets. These assets always involve multiple statuses, rules, and complex associations. It is challenging to determine the transaction execution order using the existing blockchains because they lack the ability to record and execute associations between assets, which results in problems of inconsistency of assets, such as the loss of asset status changes and status conflict between transactions. This study proposes a blockchain-native mechanism supporting complex physical assets, including a novel digital asset model and transaction validity guarantee protocol. Under the premise of ensuring safety and performance, the proposed mechanism can fully describe different associations and their influence on the transaction execution order. This study builds a global deterministic transaction execution sequence that can be executed in parallel to guarantee the consistency of complex digital assets based on partial orders. Theoretical analysis of the proposed mechanism demonstrates that it can guarantee digital asset consistency and can protect against attacks such as reentrant and transaction sequence attacks. Furthermore, experiments show that the proposed mechanism can achieve a transaction execution speed of up to 10,000 transactions per second, and this speed can be further increased by increasing the number of CPU cores.

Photodetectors with broadband optical response have promising applications in many advanced optoelectronic and photonic devices. Especially, those with the detection range up to mid-infrared at room temperature are very challenging and highly desired. Recently, Weyl semimetal has been discovered and proposed to be favorable for photodetection since in general it breaks Lorentz invariance to have tilted chiral Weyl cones around Fermi level, which leads to chirality dependent photocurrents at arbitrarily long wavelength. Furthermore, the linear dispersion bands in Weyl cones result in very high carrier mobility and much reduced thermal carrier compared with the parabolic ones in narrow-gap semiconductors. Here, we report that the Weyl semimetal TaAs based photodetector can operate at room temperature with spectral range from blue (438.5 nm) to mid-infrared (10.29 {\mu}m) light wavelengths and the responsibility and detectivity is more than 78 uA W-1 and 1.88*107 Jones, respectively. This is the first photodetector made by a Weyl semimetal and shows its promising in room-temperature mid-infrared photodetection.