Session Index

Thermal property of the optical doughnut beam generated by a stress-induced few-mode LPG is studied from 24.0 to 149.8 degree Celsius, for which the doughnut shape is virtually maintained up to 80.9 degree Celsius. The robustness of optical doughnut against temperature variation has demonstrated its potentials for applications in harsh environments.

 

Intracavity optical sensor is constructed with SOA-based fiber laser, which is used in the sensing of lateral stress. The work point is set by polarization controller for broader measuring range with improved sensitivity. As compared to the extracavity scheme, the sensitivity is increased by 10.88 times for the intracavity sensor.

 

We present a simple-processed InP/ZnSeS quantum dots/Si photodetector for the broadband white light detection. By modifying the distribution of InP/ZnSeS quantum dots, the responsivity of the photodetector can be effectively enhanced which will be a promising candidate for outdoor sensing applications

 

Enhancement of the conversion efficiency (CE) of Laser-produced plasma extreme ultraviolet (LPP-EUV) light emission at 13.5 nm is a crucial issue for large volume semiconductor manufacturing. The revised one-dimensional plasma simulation code MEDUSA is integrated with the atomic model, collisional radiative equilibrium model and the radiation transport model to investigate this multi-time scale processes of LPP-EUV light emission. The simulation framework has been validated by comparisons with some experimental results and has become an essential tool for optimizing the CE of LPP-EUV light emission.

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SHG FROG (second-harmonic frequency-resolved optical gating) is a powerful and compact tool for measuring ultrashort laser pulse characteristics. However, due to its the symmetry, it is not easy to directly determine the phase polarity. Therefore, in this paper, we set up two LEDs, which have nonlinear two-photon absorption effect and add extra dispersion to one LED. The measured power difference can be used as an indicator to reveal the measured dispersion polarity.

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Abstract: We present an experiment on laser frequency stabilization to an acetylene absorption line with Red Pitaya STEMlab. Instead of conventional bulky and expensive instruments, we apply the Lock-in PID App of Red Pitaya STEMlab to perform the modulation, phase-sensitivity detection, and PID feedback control. We successfully lock the frequency of a DFB diode laser to the center of first derivative spectrum of an acetylene V1+V3 P(9) line. The Allen deviation estimated from the residual error signal is 3 × 10-10 in a 10-s integration time.

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High-power structured beams with oval transverse morphologies and controllable order by increasing pump power are realized in a tightly-pumped Nd:YVO4 laser in a near-hemispherical resonator. By fine-tuning the cavity length in the near-hemispherical region, the aspect ratios and the detailed structures of the generated oval beams can be adjusted. Moreover, theoretical resonant modes for spherical cavities are used to reconstruct the oval beams to characterize the relation between the increasing mode order and input pump power. With the overall output power beyond 3.5 W while maintaining well-defined structures, the generated oval beams can offer promising source for future applications.

 

Table-top coherent X-ray source has drawn significant attention in recently. We propose two methods of constructing table-top X-ray source by using shock-front injection in a laser wakefield accelerator (LWFA). By using shock-front injection, the electron bunches are injected during a sharp transition of plasma density. The length of density transition is significantly shorter than the plasma wavelength and offers a highly localized injection. The first method is using a tilted shock front to break radial symmetry of injection and generate polarized betatron radiation. The second method is using a undulator to create free electron laser (FEL).

 

A tomographic technique for the growth process of high-order harmonic generation (HHG) from a laser-irradiated gas target is developed by integrating in situ measurement of the 3D phase-matching profile with interaction length control. Incorporating the phase-matching profile, calculation of HHG field emission and propagation reproduces the measured HHG growth curve as well as distinctive features of the far-field beam profiles.

 

A simple, low-cost, single-longitudinal mode C-band narrow-linewidth optical fiber laser is presented based on the Rayleigh backscattering methodology. The laser linewidth is 4.176 kHz. The optical signal-to-noise ratio is 59.86 dB, and the output power is 2.816 mW. It can easily achieve single longitude-mode output by controlling variable optical attenuator.

 

We generated ~70-kW and ~100-kW peak powers at 5.7 THz external and internal to a silicon prism coupler, respectively, atop a KTP difference-frequency generator with two pulsed narrow-spectral-width line-shape pump lasers.

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We report on the study of conventional soliton and stretched pulse in an Er3+-doped mode-locked fiber laser through the insertion of a high numerical aperture fiber for intracavity dispersion manipulation. The stretched-pulse operation with broad bandwidth has been demonstrated through the numerical simulations.

 

A Nd:YVO4 vortex laser at a wavelength of 1.3 μm is generated in a azimuthal symmetry breaking resonator of which a spiral phase plate is placed within. The vortex laser is formed as a coherent superposition of off-axis beams. In addition to a doughnut-shaped intensity distribution, the topological charge of the laser is identified to be one by interfering the vortex with its own mirror-reversal processed by Dove prism.

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Supercontinuum generation by two-mode femtosecond laser pumped nonlinear
waveguide is investigated theoretically, inparticular the superposition of a weak anomalous
dispersive mode and a strong normally dispersive mode. Adopting a nonlinear Schrodinger
equation which includes self-phase modulation, cross phase modulation and self-steepening
effect, not only dispersive wave is confirmed to emerge under the contribution of XPM but
also the spectral broadening of stong normally dispersive mode is improved.

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A continuous-wave mode-locking (CWML) laser by using intracavity sum frequency generation (SFG) with cascaded second-order Kerr lens effect is demonstrated. Adopting 15 mm long KTP crystal and type II nonphase-matched SFG process, an average power of 3.1 W at 1064 nm output was obtained under two 11.8 W diode lasers. The mode-locking pulse width was measured to be ~2.5 ns by an oscilloscope and the pulse repetition rate were observed at 170.4 MHz for both polarizations.

 

A visible light communication (VLC) using a low power 50 mW 405-nm violet laser diode (VLD) directly encoded with orthogonal frequency division multiplexed quadrature amplitude modulation (QAM-OFDM) data is demonstrated experimentally. At a distance of 0.2-m, a record data rate of up to 16 Gbit/s is obtained. The complete 4-GHz bandwidth of the 405-nm VLD was encoded with 16-QAM-OFDM data, resulting in an error vector magnitude (EVM) of 16.68 percent, a signal-to-noise ratio (SNR) of 15.57 dB, and a bit error rate (BER) of 2.75×10^-3, all of which passed the forward error correction (FEC) criterion.