On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

/pdf/the-observation-of-gravitational-waves-from-a-binary-black-58srpupgg9.pdf

The Observation of Gravitational Waves from a Binary Black Hole Merger

Our understanding of the cellular implementation of systems-level neural processes like action, thought and emotion has been limited by the availability of tools to interrogate specific classes of neural cells within intact, living brain tissue. Here we identify and develop an archaeal light-driven chloride pump (NpHR) from Natronomonas pharaonis for temporally precise optical inhibition of neural activity. NpHR allows either knockout of single action potentials, or sustained blockade of spiking. NpHR is compatible with ChR2, the previous optical excitation technology we have described, in that the two opposing probes operate at similar light powers but with well-separated action spectra. NpHR, like ChR2, functions in mammals without exogenous cofactors, and the two probes can be integrated with calcium imaging in mammalian brain tissue for bidirectional optical modulation and readout of neural activity. Likewise, NpHR and ChR2 can be targeted together to Caenorhabditis elegans muscle and cholinergic motor neurons to control locomotion bidirectionally. NpHR and ChR2 form a complete system for multimodal, high-speed, genetically targeted, all-optical interrogation of living neural circuits.

Multimodal fast optical interrogation of neural circuitry

* The only book describing applications of nonlinear fiber optics * Two new chapters on the latest developments: highly nonlinear fibers and quantum applications* Coverage of biomedical applications* Problems provided at the end of each chapterThe development of new highly nonlinear fibers - referred to as microstructured fibers, holey fibers and photonic crystal fibers - is the next generation technology for all-optical signal processing and biomedical applications. This new edition has been thoroughly updated to incorporate these key technology developments.The book presents sound coverage of the fundamentals of lightwave technology, along with material on pulse compression techniques and rare-earth-doped fiber amplifiers and lasers. The extensively revised chapters include information on fiber-optic communication systems and the ultrafast signal processing techniques that make use of nonlinear phenomena in optical fibers.New material focuses on the applications of highly nonlinear fibers in areas ranging from wavelength laser tuning and nonlinear spectroscopy to biomedical imaging and frequency metrology. Technologies such as quantum cryptography, quantum computing, and quantum communications are also covered in a new chapter.This book will be an ideal reference for: RD scientists involved with research on fiber amplifiers and lasers; graduate students and researchers working in the fields of optical communications and quantum information. * The only book on how to develop nonlinear fiber optic applications* Two new chapters on the latest developments; Highly Nonlinear Fibers and Quantum Applications* Coverage of biomedical applications

Applications of nonlinear fiber optics

Under strong laser radiation, a Dirac material, the topological insulator (TI) Bi2Te3, exhibits an optical transmittance increase as a result of saturable absorption. Based on an open-aperture Z-scan measurement at 1550 nm, we clearly show that the TI, Bi2Te3 under our investigation, is indeed a very-high-modulation-depth (up to 95%) saturable absorber. Furthermore, a TI based saturable absorber device was fabricated and used as a passive mode locker for ultrafast pulse formation at the telecommunication band. This contribution unambiguously shows that apart from its fantastic electronic property, a TI (Bi2Te3) may also possess attractive optoelectronic property for ultrafast photonics.

Ultra-short pulse generation by a topological insulator based saturable absorber

The emergence of novel two-dimensional (2D) monoelemental materials (Xenes) has shown remarkable potential for their applications in different fields of technology, as well as addressing new discoveries in fundamental science. Xenes (e.g., borophene, silicene, germanene, stanene, phosphorene, arsenene, antimonene, bismuthene, and tellurene) are of particular interest because they are the most chemically tractable materials for synthetic exploration. Owing to their excellent physical, chemical, electronic and optical properties, Xenes have been regarded as promising agents for biosensors, bioimaging, therapeutic delivery, and theranostics, as well as in several other new bio-applications. In this tutorial review, we summarize their general properties including the classification of Xenes according to their bulk properties. The synthetic and modification methods of Xenes are also presented. Furthermore, the representative Xene nanoplatforms for various biomedical applications are highlighted. Finally, research progress, challenges, and perspectives for the future development of Xenes in biomedicines are discussed.

Emerging two-dimensional monoelemental materials (Xenes) for biomedical applications

Coherent giant chirp pulse generation from Yb-doped fiber laser with excess dispersion was demonstrated. Dissipative soliton dynamics were verified as essence of giant chirp pulse with evidences of experimental characteristic spectrum and consistent theoretical modeling

Coherent Giant Chirp Pulse Generation From Mode-locked Yb-doped Fiber Laser with Excess Dispersion

We demonstrate a dual-frequency Yb3+-doped distributed Bragg reflection (DBR) fiber laser, using a homemade low reflectivity dual-wavelength fiber Bragg grating (FBG) as one of the cavity mirrors. The dual-frequency laser output is at 1063.09 nm and 1063.21 nm, with a beat frequency of 32.014 GHz.

Dual-frequency Yb 3+ -doped DBR fiber laser with 32 GHz frequency difference

Frequency-sweeping lasers have drawn considerable attentions, especially in FMCW LIDAR. The frequency sweeping single-frequency PM fiber laser is respectively realized by piezoelectric (PZT) modulation and pump modulation, which using the same Er-doped distributed Bragg reflection (DBR) fiber cavity. The central wavelength is 1552.49 nm with the extinction ratio of above 20 dB. The frequency sweeping range of PZT modulation is seen to be up to 745 MHz under the modulation repetition rate of 1Hz, and the modulation repetition rate of the pump can be tuned from 1Hz to 20 kHz. However, the frequency sweeping range and tunable range of pump modulation is 635 MHz and from 1Hz to 10 kHz, respectively. Comparing with both methods, the PZT modulation has wider sweeping range and tunable range, however, the mechanical resonance will be occurred. The pump modulation indicates virtually linearly frequency modulation. Future works to achieve more characteristic of two modulation methods are undergoing.

Frequency-sweeping single-frequency polarization-maintaining Er-doped fiber laser for FMCW lidar

We report on 2.5 cycle pulse compression from 60 to 15 fs at 1800 nm in the fundamental mode of an Ar-filled low-loss antiresonant hollow-core fiber by pumping close to strand-resonance and zero dispersion wavelength.

2.5 Cycle Pulses Obtained With Self Compression At 1.8 μm In Antiresonant Waveguides

We demonstrated that SESAM mode-locked thulium-doped fiber laser produced stable nanosecond pulses from 2.5ns to 12.5ns at repetition rates between 1.72MHz and 258kHz. Average power of 5.6W at 1942nm was obtained by two-stage all-fiber amplifiers.

Pu Wang

Papers

Coherent Giant Chirp Pulse Generation From Mode-locked Yb-doped Fiber Laser with Excess Dispersion

Dual-frequency Yb 3+ -doped DBR fiber laser with 32 GHz frequency difference

Frequency-sweeping single-frequency polarization-maintaining Er-doped fiber laser for FMCW lidar

2.5 Cycle Pulses Obtained With Self Compression At 1.8 μm In Antiresonant Waveguides

Generation and amplification of stable nanosecond pulses in a thulium-doped fiber laser