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Damping as well as following control of nanopositioning periods with double postponed position suggestions.
We propose a novel, to the best of our knowledge, method to enhance the measurement range of dynamic strain using a single-slope-assisted chaotic Brillouin optical correlation-domain analysis. The broadband chaos provides a Gaussian-shape pump-probe beat spectrum so that not only the centimeter-level spatial resolution is achieved but also the linewidth of the chaotic Brillouin gain spectrum is naturally broadened. Thus, the enlarged linear region could be employed to dynamically measure a large-range stretched strain. This experiment is the first to accurately identify the maximal strain of 1200 $unicodex00B5unicodex03B5$µε with a high spatial resolution of 3.45 cm using the single-slope-assisted technology. The dynamic frequency is 4.67 Hz in the highest but limited by the practical devices.A 100 W level kilohertz repetition-rate microsecond (µs)-pulse all-solid-state sodium beacon laser at 589 nm is demonstrated for the first time, to the best of our knowledge, via combining two independent µs-pulsed lasers. Each beamlet is generated by the sum-frequency mixing of pulsed 1064 and 1319 nm lasers in a lithium triborate (LBO) crystal, which operate at 500 Hz pulse repetition frequency with 61 W $p$p-polarized and 53 W $s$s-polarized output, respectively. An incoherent sequence combining technology of polarized laser beams is employed to add the two beamlets. The average power of the combined beam is up to 107.5 W with a combining efficiency of 94.3%. The combined beam has a 1 kHz repetition rate with $sim120;unicodex00B5 rm s$∼120µs pulse duration and beam quality $M^2 = 1.41$M2=1.41. The central wavelength with a linewidth of $sim0.3;rm GHz$∼0.3GHz is locked to a sodium $rm D_2a$D2a absorption line. To the best of our knowledge, this is a record-high power operating at kilohertz for µs-pulsed solid-state sodium beacon lasers.In this work, the nonlinear optical (NLO) response of some graphene dispersions is investigated under low (i.e., 10 Hz) and high (i.e., 80 MHz) repetition rate femtosecond (fs) laser excitation conditions, using $Z$Z-scan, optical Kerr effect (OKE), and a combination of $Z$Z-scan and thermal lensing techniques. It is shown, that the NLO response of graphene dispersions is negligible under low repetition rate fs laser excitation, while it becomes very large under high repetition rate laser excitation. In the latter case, it is shown that the observed very large NLO response arises entirely from thermal cumulative effects.Two generation mechanisms-optical perturbation and acoustic radiation force (ARF)-were investigated where high frame rate ultrasound imaging was used to track the propagation of induced SAWs. We compared ARF-induced SAWs with laser-induced SAWs generated by laser beam irradiation of the uniformly absorbing tissue-like viscoelastic phantom, where light was preferentially absorbed at the surface. We also compared the frequency content of SAWs generated by ARF versus pulsed laser light, using the same duration of excitation. Differences in the SAW bandwidth were expected because, in general, laser light can be focused into a smaller area. Finally, we compared wave generation and propagation when the wave's origin was below the surface. We also investigated the relationship between shear wave amplitude and optical fluence. The investigation reported here can potentially extend the applications of laser-induced SAW generation and imaging in life sciences and other applications.Here, we demonstrate an all-silicon photonic switch, working at an infrared communication wavelength and pumped by spatial light, where a ring resonator and a metasurface absorber are both designed in photonic crystals and monolithically integrated on a silicon-on-insulator wafer. Through selective doping, the absorber gets a pump absorption completely different from near zero of the resonator. Based on the thermo-optical effect, the device is capable of tuning the wavelength of the guided mode by $sim341;rm pm/mW$∼341pm/mW and switching in time $ lt 1.0;unicodex00B5 rm s$ less then 1.0µs to the pump response. The high responsivity and switching speed as well as all-silicon processing techniques make the design potentially for free-space optical communication and detection.A source of hyper-entangled photons plays a vital role in quantum information processing, owing to its high information capacity. In this Letter, we demonstrate a convenient method to generate polarization and orbital angular momentum (OAM) hyper-entangled photon pairs via spontaneous four-wave mixing (SFWM) in a hot $ ^87rm Rb $87Rb atomic vapor. The polarization entanglement is achieved by coherently combining two SFWM paths with the aid of two beam displacers that constitute a phase self-stabilized interferometer, and OAM entanglement is realized by taking advantage of the OAM conservation condition during the SFWM process. Our hyper-entangled biphoton source possesses high brightness and high nonclassicality and may have broad applications in atom-photon-interaction-based quantum networks.Microlens arrays (MLAs) are widely used in optical imaging, dense wavelength division multiplexing, optical switching, and microstructure patterning, etc. However, the light modulation capability for both the conventional refractive-type MLA and planar diffractive-type MLA is still staying at the diffraction-limited scale. Here we propose and experimentally demonstrate a high numerical aperture (NA) supercritical lens (SCL) array which could achieve a sub-diffraction-limited focal spot lattice in the far field. The intensity distribution for all the focal spots has good uniformity with the lateral size around $0.45lambda rm /NA$0.45λ/NA (0.75X Airy unit). The elementary unit in the SCL array composes a series of concentric belts with a feature size in micrometer scale. By utilizing an ultrafast ultraviolet lithography technique, a centimeter scale SCL array could be successfully patterned within 10 mins. Our results may provide possibilities for the applications in optical nanofabrication, super-resolution imaging, and ultrafine optical manipulation.We experimentally demonstrate Kramers-Kronig detection of four 20 Gbaud 16-quadrature-amplitude-modulated (QAM) channels after 50 km fiber transmission using two soliton Kerr combs as signal sources and local oscillators. The estimated carrier phase at the receiver for each of the channels is relatively similar due to the coherence between the frequency comb lines. The standard deviation of the estimated carrier phase difference of the channels is less than 0.08 rad after 50 km single-mode fiber (SMF) transmission. This enables the carrier phase recovery derived from one channel to be shared among multiple channels. In the back-to-back scenario, the bit error rate (BER) performance for shared carrier phase recovery shows an optical signal-to-noise ratio penalty of $sim0.5;rm dB$∼0.5dB compared to the BER performance for carrier phase recovery when derived for each channel independently. BERs below the forward error correction threshold are achieved after 50 km SMF transmission with both independent and shared carrier phase recovery for four 20-Gbaud 16-QAM signals.In this Letter, we report a segmented large-scaled lightweight diffractive telescope testbed newly built in our laboratory. The telescope, consisting of one 710-mm-diameter element in the center surrounded by eight 352-mm-diameter elements and a smaller eyepiece of achromatic lenses, can realize wide-band high-resolution imaging of 0.55-0.65 µm. The stitching errors are coarsely corrected by adjusting the motion stage mounted on each element. In particular, an optical synthesis system inserted behind the eyepiece is designed to compensate the residual tip-tilt-piston errors. We present the experimental imaging result of two stitched elements, which is the first successful experimental verification obtained by a practical segmented diffractive telescope to enhance the resolution. Moreover, spatial modulation diversity technology is used to restore the synthetic image so as to improve its quality and contrast.A flat-amplitude multi-wavelength random Raman fiber laser with broad spectral coverage and a high optical signal-to-noise ratio (OSNR) is challenging and of great interest. In this Letter, we theoretically and experimentally proved that broadband pumping can help realize a broader, flat-amplitude multi-wavelength random Raman fiber laser. The influence of pump bandwidth, tunability of the spectral envelope, and channel spacing are investigated. As a result, with a 40 nm pump bandwidth, a spectral coverage of 1116-1125 nm with 19 laser lines and 31 dB OSNR is achieved, and the standard deviation in the peak intensities of the central nine lines is $sim1.1;rm dBm$∼1.1dBm. This technique can also be applied to the multi-wavelength Raman (or random Raman) fiber lasers at other wavelengths and provide a reference for multi-wavelength applications in sensing, communication, and optical component testing.In this Letter, we propose and realize a novel concept for a high-peak-power highly efficient fiber amplifier in the 1.55 µm spectral range. The amplifier is based on the simultaneous utilization of Er-doped, Yb-free, and Er-Yb codoped large-mode-area fibers spliced together. Using this approach, we demonstrate the amplification of single-frequency 160 ns pulses at 1554 nm to a peak power of 3.7 kW with a pump-to-signal conversion efficiency of 23.6% relative to the launched multimode pump power at 976 nm.Microwave metasurfaces comprising overlapping layers of circular patches arranged in a hexagonal array are found to support edge modes akin to edge plasmons. The coupling of these edge modes across small gaps between two such arrays is explored. learn more This phenomenon, well known at optical frequencies, is verified here for the first time, to the best of our knowledge, at microwave frequencies.We describe theoretically and verify experimentally a novel, to the best of our knowledge, class of diffraction-free pulsed optical beams that are "omni-resonant" they have the remarkable property of transmission through planar Fabry-Perot resonators without spectral filtering, even if their bandwidth far exceeds the cavity linewidth. Ultrashort wave packets endowed with a specific spatiotemporal structure couple to a single resonant mode independent of its linewidth. We confirm that such "space-time" omni-resonant wave packets retain their bandwidth (1.6 nm), spatiotemporal profile (1.3-ps pulse width, 4-µm beam width), and diffraction-free behavior upon transmission through cavities with resonant linewidths of 0.3 nm and 0.15 nm.Monoclinic (wolframite-type) monotungstate crystals are promising for rare-earth doping. We report polarized room- and low-temperature spectroscopy and efficient high-power laser operation of such a $rm Yb^3 + ,rm MgWO_4$Yb3+MgWO4 crystal featuring high stimulated emission cross section ($sigma _rm SE; = ;6.2; times ;10^ - 20;rm cm^2$σSE=6.2×10-20cm2 at 1056.7 nm for light polarization $rm E;||;N_m$E||Nm), large Stark splitting of the ground state ($765;rm cm^ - 1$765cm-1), large gain bandwidth (26.1 nm for $rm E;||;N_g$E||Ng), and strong Raman response (most intense mode at $916;rm cm^ - 1$916cm-1). A diode-pumped $rm Yb^3 + ,rm MgWO_4$Yb3+MgWO4 laser generated 18.2 W at $sim1056;rm nm$∼1056nm with a slope efficiency of $sim89% $∼89% and a linearly polarized laser output.
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