Session Index

The study investigates the current gain (β) and optical light output between InGaP / GaAs light-emitting transistors (LETs) at different temperatures. From ambient temperature to 358K, the Darlington LET's current gain (β) improves 94.11％, which is desirable for the high resolution smart thermal sensor. Finally, we made the first optoelectrical amplifier in the world using LET.

 

We report the design and fabrication of a dielectric-grating waveguide driven by 40-keV electrons to emit narrow-line radiation at 0.56 THz. With a current density of 8 A/cm2, the coherent THz radiation builds up from bunched electrons in about 2 ns.

 

We generate and analyze random-modulated pulses based on the transient response of a gain-switched semiconductor laser and homodyne interference for pulsed lidar applications. Benefited by the low-correlated waveforms, lidars utilizing random-modulated pulses possess the advantages of no range ambiguity and immune to interference. With proper control of the laser drive current and the length of the homodyne delay, we successfully generate low-correlated random-modulated pulses suitable for the pulsed lidar applications. In compliance with the class-1 eye-safe regulation, 3D imaging with millimeter precision revealing the details of a hand is demonstrated.

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Bound states in the continuum (BIC) have been attracted scientists to study intensive research due to its unique characteristics which are significant for both fundamental physics and practical applications. By using the mechanism of Friedrich-Wintgen BIC, we can realize the off-normal lasing with variable emission angles.

 

We demonstrate an on-chip heralded single photon source based on a type-II periodically poled lithium niobate (PPLN) spontaneous parametric down-converter (SPDC) and a 7-waveguide adiabatic coupler system, integrated in a Ti-diffused LiNbO3 waveguide platform. The PPLN SPDC generates cross-polarized photon pairs when pumped at 785 nm, while the adiabatic coupler system works both as a pump filter and a broadband polarizing mode splitter. The photon pair generation rate of such an integrated SPDC source is estimated to ~10^4 s^(-1) at a pump power of 4.5 uW.

 

Nonlinear pulse compression is used to generate 23 fs, 0.44 mJ ultrafast green pulses from an Yb:KGW solid state regenerative amplifier. By passing through an Ar-filled gas filled chamber, the original spectrum is broadened. Then, chirp mirrors are used to compensate the spectral phases.

 

Thin-film lithium niobate enables to combine the advantages of the lithium niobate material with nanoscale optical elements. Here, I will review our recent results in the realization of nanostructured lithium-niobate components for nonlinear frequency conversion. Special emphasis is on the use of these structures as sources of correlated photon-pairs.

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We show that the speckle phase error incurred when the laser spot is scanned over the diffusing surface can be made as low as 10..20-m for object sizes in the range 3..10-cm. This result is new, at the best of our knowledge, because it is usually assumed that when the spot moves of its size the phase becomes uncorrelated and the measurement can't be done anymore. We carry out numerical simulations of the process, and derive an analytical model to evaluate the phase error and the NED (noise equivalent displacement) of the profile measurement by SMI (self-mixing interferometer).

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We present the study of a near-infrared free-electron laser consisting of a 31-um long dielectric grating with a 310-nm grating period in a 400-nm thick silicon waveguide on a glass substrate. When driven by a ~50-keV electron flying 100 nm above the structure, the nano-grating generates a laser-like radiations at ~1.5 micron via Bragg and backward-wave resonances. This work paves the way to miniaturize a bulky free-electron laser to a chip-size device.

 

Strong coupling between an atom and a cavity has been utilized for quantum photonic devices. The alignment between an atom and a cavity needs atom trapping and high vacuum equipment, which are hardly to be integrated into a microchip. Here, DNA strands are used to connect a gold nanoparticle and a gold film to construct a nanocavity and simultaneously integrate a few fluorophores to form a strong coupling unit. This method produces high cavity yield and strong coupling yield. Combination of this method with e-beam lithography can further position strong coupling units on a specific location of a microchip.


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We fabricated a high-power distributed feedback (DFB) laser. In the experiment, the measured temperature and the injected current are changed, we observed the difference in the frequency spectrum. In the microwave measurement, it is found that the switching between DFB mode and FP mode will affect the oscillation frequency.

 

In this study, we design the structure of flip-chip tunnel junction VCSEL to improve speed, output power and conversion efficiency for medium and long-distance sensing. Through the design of flip-chip structure and tunnel junction, the PCE can improve to 57.8%.

 

Simultaneous multi-peak yellow-orange laser based on monolithic Nonlinear Photonic Crystals(NPCs) was demonstrated. The temperature bandwidth(FWHM) of our design could reach near ten degree and slope efficiency was over 8.5%. Furthermore, the number of peaks could be controlled by modulating the periodicities of the OPO and SHG/SFG part.

 

We demonstrated the THz wavelength tuning between 5.43 and 6.1 THz without aligning. By strongly focusing the seed laser, the optical path can satisfy the momentum conservation of non-collinear phase matching in a THz parametric amplifier. The measured maximum output THz energy was ~2.26 μJ at 5.7 THz.

 

Utilizing intracavity optical parametric oscillator (OPO) is an efficient method for generating continuous-wave mid-IR laser. However, when the solid-state gain medium was utilized as the parent pumped near-IR source, serious self-pulsing well be observed due to the strong coupling between relaxation oscillation and OPO depletion. In this work, optically pumped semiconductor laser is employed to overcome the self-pulsing issue. Theoretically analysis is also performed to verify the experimental result.

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The relative intensity noise (RIN) spectrum is a parameter that can be used to choose a vertical-cavity surface-emitting laser (VCSEL) for transmission. The RIN measurement is from 100Mz to 20GHz. However, this range may ignore the frequency response higher than 20GHz, and affect the performance of VCSEL.

 

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This letter presents the static and microwave characteristics, 100 GBase-SR4 eye mask margins, and eye diagrams of volume manufacturable 850-nm oxide confined VCSELs with 7 μm diameter oxide aperture. The VCSELs with high dynamics performance design enable high-quality eye diagrams with 25.781 Gbps on-off-keying (OOK) and 28 Gbaud 4-level pulse amplitude modulation (PAM-4) at room temperature and 75 °C without pre-emphasis, digital signal processing, and any equalization.

 

We have successfully demonstrated a 10/20 GHz all-PM Figure-9 hybrid mode-locked Er-doped fiber
laser. With the help of a nonreciprocal phase shifter in the fiber loop, stable mode-locked pulse trains are
obtained under the high repetition rates and the pulse-width can be as short as 1.7 ps.

 

This study uses the 2D electro-optical numerical model developed by our laboratory to analyze the electrical characteristics and optical field distribution for different designs of ridged semiconductor laser diodes. By changing the design of the structure beside the ridge, the difference of model gain properties are discussed.

 

We employ the selectively pumped solid-state laser with the stimulated Raman scattering and second-harmonic generation to generate the frequency-doubled Hermite-Gaussian modes (FDHGMs) at 588nm. The FDHGMs are transformed by using an external cylindrical mode converter to generate various structured lights with multiple optical vortices. It is demonstrated that the number of vortices can be raised from 2 to 9 with increasing off-center displacements.

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We employ the selectively pumped solid-state laser with the stimulated Raman scattering and second-harmonic generation to generate the frequency-doubled Hermite-Gaussian modes (FDHGMs) at 588nm. The FDHGMs are transformed by using an external cylindrical mode converter to generate various structured lights with multiple optical vortices. It is demonstrated that the number of vortices can be raised from 2 to 9 with increasing off-center displacements.

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We employ an off-axis pumped Nd:YVO4 laser with stimulated Raman scattering and second harmonic generation to generate frequency-doubled Hermite-Gaussian modes at 589 nm. By using an astigmatic mode converter (AMC), the generated frequency-doubled Hermite-Gaussian modes are straightforwardly transformed into corresponding Hermite–Laguerre Gaussian modes with multiple vortices. Furthermore, we can control spatial distribution of the optical vortices by rotating the angle of the AMC.

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The two photon absorption (TPA) of ligand modified CsPbBr3 QDs film has been demonstrated from TPA PL measurement, which shows the quadratic depend on pump intensity. Through the z-scan measurement, the normalized transmittance reveals a symmetric dip with relative large TPA coefficient about 4.71×103 cm/GW than previous reports.

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The ultrathin perovskite paper enables the color-converted white-lighting of an 80-mW blue laser diode without severely compromising its encoding bandwidth to demonstrate a 10.8-Gbit/s 8-QAM-OFDM optical wireless data link over 0.3-m free-space after waveform pre-leveling.

 

The multimode vertical cavity surface emitting laser (MM-VCSEL) produced with 7.5 um oxide-confined aperture is performed for intra-data-center application. By employing bit loading discrete multi-tone (DMT) data streams, the data rate can boost up to 145 Gbit/s. When operating at 55oC, the degraded output power and encodable bandwidth of the MM-VCSEL under heating limits its maximal data rate to 130 Gbit/s.

 

Terahertz plays a pivotal part in numerous technology fields in modern times. In addition to light source and detector, THz application requires guiding devices such as lenses, waveguides, and reflectors. The absorptivity of the common 3D printer materials is larger than 5 cm-1 which does not match the requirement of high refractive index and low absorption rate producing lenses. In the study, it's found that the mixture of ABS powder and the rice husk ash (RHA) which is composed of SiO2 decreases the absorption rate effectively. Therefore, it is suitable for 3D printer materials on making a lens of THz.

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We demonstrated the optimization of blue diode-pumped Pr:YLF laser by varying mode overlap between pumping mode and cavity mode. When the pumping power was 1.2W, the output power and slope efficiency were achieved to 204.2mW and 34.1% respectively.

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We report a novel fast optical switch in a LiNbO3 photonic-circuit chip integrating an electro-optic (EO) polarization mode converter and a broadband adiabatic polarizing beam splitter. A high power-switching efficiency of ~95% can be obtained over a broad bandwidth of >100 nm (1520-1620 nm) via the temperature tuning with an EO switching voltage of ~20 V. Such a device can be of potential interest to quantum photonic manipulation when further integrated with a type-II spontaneous parametric down-conversion source.

 

In semiconductor heterostructures, such as GaN / AlGaN structures, there is a layer of two-dimensional electron gas (2DEG), which can be used as an electron source. The Electrons in two-dimensional electron gas can be attracted by an external electric field is transported to the receiver through a zero-potential track, and a series of current pulses generated by electron transmission are generated at the receiver.

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We explore the effects of cavity loss on the morphologies of Lissajous modes generated in a diode-end-pumped Nd:YVO4 laser by varying the cavity output transmittance. Experimental results show that Lissajous mode patterns gradually break into several segments with the growing cavity loss due to the photon decoherence. By further using theoretical resonant modes of the spherical cavity, the experimental observations are well reconstructed to give a quantitatively relation between the system dissipation and output transmittance for studying structured photon decoherence in the future.

 

This study investigates broad-band, high-entropy chaos generation using a semiconductor laser subject to intensity-modulated optical injection for true physical random bit generation. The proposed chaotic source can be used as a 2-bit true physical random bit generator at a rate of 160 Gb/s with guaranteed unpredictability.

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We theoretically explore the mechanism in a thulium Q-switched ytterbium-doped all-fiber fiber laser using a set of rate equations to model the correlations between the photons and the five energy levels of thulium involved in the Q-switching mechanism. We demonstrate that by coupling with a gain-switched resonator, the Q-switched laser is stabilized up to the maximum pulsing rate that is limited by the lifetime of level 3H5. To the best of our knowledge, this is the first study that revealed that level 3H5 plays an essential role in re-initialization, achieving sequential pulses and limiting the maximum repetition rate.

 

We present a novel 7 × 1 fiber laser combiner for high-power fiber laser by using a glass tube bundling method and micro-nano structure technique. A high output power of 4210 W is obtained by launching a power of 4240 W using four near-single mode Yb-doped fiber lasers (YDFLs) with operating at wavelength of 1070 nm.

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In this manuscript, we demonstrate our 940 nm VCSELs (vertical-cavity surface-emitting
lasers) with a peak optical output of 7.2 W under pulsed operation. The 50 devices are
arranged in a unique binary pattern distribution design for improved sensing applications.

 

Laser material processing for structure at micrometer level includes various phenomenon, such as photochemical, photothermal, photoablation and photodisruption, depending on laser and material parameters. Different high frequency substrate materials are studied in this paper. After the laser pulse energy is absorbed, the thermal model is used to simulate result of laser processing. Furthermore, due to the material optical properties, the multiphoton-excited fluorescence microscopy (MPEFM) could reconstruct the material fluorescence images for the 3D processed structure.

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In this paper we report the development of an all-fiber-format sub-megawatt-peak-power femtosecond light source at 1250 nm for clinical imaging. Driven by a Yb-fiber laser, we successfully generated 34 fs 1244 nm pulses with a 13.3 nJ pulses energy through self-phase modulation in a photonics crystal fiber in the weak negative dispersion region.

 

In this paper, we have investigated the simulation-based study of InGaP/GaAs heterojunction bipolar transistor (HBT) structure having 12 nm-In0.2Ga0.8As as quantum well in its base. The current gain of QW-HBTs is enhanced around ~248% with the increasing temperature from 300 K to 400 K, which characteristic is opposite to the simple HBTs based structure. The thermally-enhanced current gain is achieved by using the capture-escape model, parabolic quantum well model, Luttinger-Kohn k.p. model in the simulation. This study makes the application of QW-HBTs structure on the design of a smart thermal sensor promising.

 

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.

 

The ultrashort pulse laser is composed of many components of different frequency which have different propagate speed in material because of different frequency. The result called dispersion. In this paper, we take frequency resolve optical gating(FROG) to measure the ultrashort pulse information. Using 4-f pulse shaper system which compose of a blaze grating and a 39 channel linear deformable mirror to achieve pulse compression

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In this study, we investigated the lasing characteristics of Photonic-Crystal Surface-Emitting Laser (PCSEL) with honeycomb lattice. The light-current-voltage (L-I-V) performance, lasing spectrum, far-field patterns, and the photonic band diagram were analyzed both theoretically and experimentally. Furthermore, the laser beam featuring with orbtial angular momentum (OAM) was predicted from the numerical simulation and observed from the far-field pattern, which gives rise to more extensive applications.

 

A 10 GHz active mode-locked Er-doped fiber laser is stabilized by a high Finesse Fabry-Pérot etalon. The output pulses are nonlinearly compressed from 15 ps down to 2 ps by using the high nonlinearity fiber (HNF) combined with the single mode fiber (SMF). Excellent agreement between the simulation and experimental results is achieved. The simulation also indicates that the stationary rescale pulse scheme can be utilized to further compress the pulse width down to 500 fs if multiple stages of HNF+SMF are used.

 

He^1+ based high-harmonic generation operated from water window to keV spectral range is proposed. The selective-zoning method of quasi-phase-matching is utilized to overcome the severe plasma dispersion in the highly ionized medium. Our calculation shows that the relative conversion efficiency reaches about 15% of the perfect phase-matching condition. Wavelength tunability is achieved by incorporating a programmable spatial-light modulator to control the quasi-phase-matching pattern.

 

Terawatt level CO2 laser is considered a promising tool for proton acceleration. We choose a new approach to construct a high-energy seeding system for large-aperture CO2 amplifiers based on nonlinear mixing of 1.3-µm and 1540-nm pulses. In this paper we report
the performance of a Nd:YAG disk-based regenerative amplifier seeded by an electrically synchronized 700-ps, 1338-nm gain-switched diode laser. The seeded amplifier produces an output energy of ∼3.5-mJ with a timing jitter of ∼30-ps-rms, sufficient for smoothing the comb-like spectrum of CO2 amplifiers by power broadening.