Diploid chromosome-level reference genome and population genomic analyses provide insights into Gypenoside biosynthesis and demographic evolution of Gynostemma pentaphyllum (Cucurbitaceae)

Gynostemma pentaphyllum(Thunb.)Makino is a perennial creeping herbaceous plant in the family Cucurbitaceae,which has great medicinal value and commercial potential,but urgent conservation efforts are needed due to the gradual decreases and fragmented distribution of its wild populations.Here,we report the high-quality diploid chromosome-level genome of G.pentaphyllum obtained using a combination of next-generation sequencing short reads,Nanopore long reads,and Hi-C sequencing technologies.The genome is anchored to 11 pseudo-chromosomes with a total size of 608.95 Mb and 26588 predicted genes.Comparative genomic analyses indicate that G.pentaphyllum is estimated to have diverged from Momordica charantia 60.7 million years ago,with no recent whole-genome duplication event.Genomic population analyses based on genotyping-by-sequencing and ecological niche analyses indicated low genetic diversity but a strong population structure within the species,which could classify 32 G.pentaphyllum populations into three geographical groups shaped jointly by geographic and climate factors.Furthermore,comparative transcriptome analyses showed that the genes encoding enzyme involved in gypenoside biosynthesis had higher expression levels in the leaves and tendrils.Overall,the findings obtained in this study provide an effective molecular basis for further studies of demographic genetics,ecological adaption,and systematic evolution in Cucurbitaceae species,as well as contributing to molecular breeding,and the biosynthesis and biotransformation of gypenoside.

On-chip programmable pulse processor employing cascaded MZI-MRR structure

Optical pulse processor meets the urgent demand for high-speed,ultra wideband devices,which can avoid electrical confinements in various fields,e.g.,alloptical communication,optical computing technology,cohcrcnt control and microwave fields.To date,great efforts have been madc particularly in on-chip programmable pulse proccessing.Here,we experimentally demonstrate a programmable pulse proceesor employing 16cascaded Mach-Zehnder interferometer coupled microring resonator(MZI-MRR)structure based on silicon-oninsulator wafer.With micro-heaters loaded to the device,both amplitude and frequency tunings can be realized in each MZI-MRR unit.Thanks to its reconfigurability and integration ability,First,it can serve as a fractional differentiator whose tuning range is 0.51-2.23 with deviation no more than 7%.Second,the device can be tuned into a programmable optical filter whose bandwidth varies from 0.15to 0.97nm.The optical filter is also shape tunable.Especially,15-channel wavelength selective switches are generated.

Tunable optical delay line based on integrated grating-assisted contradirectional couplers

Tunable optical delay lines are one of the key building blocks in optical communication and microwave systems.In this work, tunable optical delay lines based on integrated grating-assisted contradirectional couplers are proposed and experimentally demonstrated. The device performance is comprehensively improved in terms of parameter optimization, apodization analysis, and electrode design. Tunable group delay lines of 50 ps at different wavelengths within the bandwidth of 12 nm are realized with a grating length of 1.8 mm. Under thermal tuning mode, the actual delay tuning range is around 20 ps at 7.2 V voltage. At last, a new scheme adopting an ultra-compact reflector for doubling group delay is proposed and verified, achieving a large group delay line of 400 ps and a large dispersion value up to 5.5 × 10~6 ps∕(nm · km) within bandwidth of 12 nm. Under thermal tuning mode, the actual delay tuning range is around 100 ps at 8 V voltage.

A small microring array that performs large complex-valued matrix-vector multiplication

As an important computing operation,photonic matrix-vector multiplication is widely used in photonic neutral networks and signal processing.However,conventional incoherent matrix-vector multiplication focuses on real-valued operations,which cannot work well in complex-valued neural networks and discrete Fourier transform.In this paper,we propose a systematic solution to extend the matrix computation of microring arrays from the real-valued field to the complex-valued field,and from small-scale(i.e.,4×4)to large-scale matrix computation(i.e.,16×16).Combining matrix decomposition and matrix partition,our photonic complex matrix-vector multiplier chip can support arbitrary large-scale and complex-valued matrix computation.We further demonstrate Walsh-Hardmard transform,discrete cosine transform,discrete Fourier transform,and image convolutional processing.Our scheme provides a path towards breaking the limits of complex-valued computing accelerator in conventional incoherent optical architecture.More importantly,our results reveal that an integrated photonic platform is of huge potential for large-scale,complex-valued,artificial intelligence computing and signal processing.