Normal-mode splitting in the optomechanical system with an optical parametric amplifier and coherent feedback

Strong coupling in optomechanical systems is the basic condition for observing many quantum phenomena such as optomechanical squeezing and entanglement. Normal-mode splitting (NMS) is the most evident signature of strong coupling systems. Here we show the NMS in the spectra of the movable mirror and the output field in an optomechanical system can be flexibly engineered by a combination of optical parametric amplifier (OPA) and coherent feedback (CF). Moreover, the NMS could be enhanced by optimizing the parameters such as input optical power, OPA gain and phase, CF strength in terms of amplitude reflectivity of beam splitter.Comment: 8 pages, 7 figure

An outlook to sophisticated technologies and novel developments for metabolic regulation in the Saccharomyces cerevisiae expression system

Saccharomyces cerevisiae is one of the most extensively used biosynthetic systems for the production of diverse bioproducts, especially biotherapeutics and recombinant proteins. Because the expression and insertion of foreign genes are always impaired by the endogenous factors of Saccharomyces cerevisiae and nonproductive procedures, various technologies have been developed to enhance the strength and efficiency of transcription and facilitate gene editing procedures. Thus, the limitations that block heterologous protein secretion have been overcome. Highly efficient promoters responsible for the initiation of transcription and the accurate regulation of expression have been developed that can be precisely regulated with synthetic promoters and double promoter expression systems. Appropriate codon optimization and harmonization for adaption to the genomic codon abundance of S. cerevisiae are expected to further improve the transcription and translation efficiency. Efficient and accurate translocation can be achieved by fusing a specifically designed signal peptide to an upstream foreign gene to facilitate the secretion of newly synthesized proteins. In addition to the widely applied promoter engineering technology and the clear mechanism of the endoplasmic reticulum secretory pathway, the innovative genome editing technique CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated system) and its derivative tools allow for more precise and efficient gene disruption, site-directed mutation, and foreign gene insertion. This review focuses on sophisticated engineering techniques and emerging genetic technologies developed for the accurate metabolic regulation of the S. cerevisiae expression system

Bi2Te3/Graphene Heterostructure as the Saturable Absorber for ~1.0 μm Passively Q-switched Solid State Pulsed Laser

Due to the tunable nonlinear optical properties of the Bi2Te3/graphene heterostructure, stable solid state pulsed lasers based on the Bi2Te3/graphene saturable absorber have attracted intensive attention. In this work, the Bi2Te3/graphene heterostructure with good nonlinear absorption characteristics was synthesized by a self-assembly solvothermal route, and the optical saturable absorption properties of the saturable absorber were investigated. Owing to the large modulation depth of Bi2Te3 nanosheets and the high thermal conductivity of graphene, the Bi2Te3/graphene heterostructure saturable absorber shown good nonlinear saturable absorber performance and contributed the improved passively Q-switched Yb3+: GdAl3(BO3)4 pulsed laser when compared with that of the pure Bi2Te3 based Yb3+: GdAl3(BO3)4 laser, no matter pulse width or pulse energy. Our work demonstrates that the Bi2Te3/graphene heterostructure was a promising saturable absorber in ~1 μm solid-state pulsed lasers

Bi₂Te₃/Graphene Heterostructure as the Saturable Absorber for ~1.0 <i>μ</i>m Passively Q-switched Solid State Pulsed Laser

Due to the tunable nonlinear optical properties of the Bi2Te3/graphene heterostructure, stable solid state pulsed lasers based on the Bi2Te3/graphene saturable absorber have attracted intensive attention. In this work, the Bi2Te3/graphene heterostructure with good nonlinear absorption characteristics was synthesized by a self-assembly solvothermal route, and the optical saturable absorption properties of the saturable absorber were investigated. Owing to the large modulation depth of Bi2Te3 nanosheets and the high thermal conductivity of graphene, the Bi2Te3/graphene heterostructure saturable absorber shown good nonlinear saturable absorber performance and contributed the improved passively Q-switched Yb3+: GdAl3(BO3)4 pulsed laser when compared with that of the pure Bi2Te3 based Yb3+: GdAl3(BO3)4 laser, no matter pulse width or pulse energy. Our work demonstrates that the Bi2Te3/graphene heterostructure was a promising saturable absorber in ~1 μm solid-state pulsed lasers

Crystal growth and spectral properties of Nd3+/Er3+: CaLaAl0.6Ga2.4O7 crystal for a 2.7 mu m laser

Nd3+/Er3+: CaLaAl0.6Ga2.4O7 (abbr. as Nd3+/Er3+: CLAGO) crystal was firstly grown by Czochralski method. The 2.7 mu m fluorescence emission properties and energy transfer mechanism of this crystal were investigated. Besides better absorption characteristic, the spectra of Nd3+/Er3+: CLAGO show much weaker near-infrared emission as well as superior mid-infrared emission in comparison to Er3+: CLGO. Furthermore, the self-termination bottleneck for Er-3(+) 2.7 mu m laser was greatly decreased in Nd3+/Er3+: CLAGO crystal and the energy transfer efficiencies of Nd3+: F-4(3/2) -> Er3+: I-4(11/2) and EP + : I-4(13/2) -> Nd3+: I-4(15/2) were determined. In the best case, the above four advantages indicate that the Nd3+/Er3+: CLAGO crystal might be suitable for pulsed operation and a promising 2.7 mu m laser medium

Generalizing Quantile Regression for Counting Processes With Applications to Recurrent Events

<p>In survival analysis, quantile regression has become a useful approach to account for covariate effects on the distribution of an event time of interest. In this article, we discuss how quantile regression can be extended to model counting processes and thus lead to a broader regression framework for survival data. We specifically investigate the proposed modeling of counting processes for recurrent events data. We show that the new recurrent events model retains the desirable features of quantile regression such as easy interpretation and good model flexibility, while accommodating various observation schemes encountered in observational studies. We develop a general theoretical and inferential framework for the new counting process model, which unifies with an existing method for censored quantile regression. As another useful contribution of this work, we propose a sample-based covariance estimation procedure, which provides a useful complement to the prevailing bootstrapping approach. We demonstrate the utility of our proposals via simulation studies and an application to a dataset from the U.S. Cystic Fibrosis Foundation Patient Registry (CFFPR). Supplementary materials for this article are available online.</p