High beam quality continuous-wave 320 nm UV laser from a walk-off compensated intracavity frequency-doubled Pr:YLF laser.

We report a high beam quality continuous-wave (CW) 320 nm ultra-violet (UV) laser. An end-pumped praseodymium-doped yttrium lithium fluoride (Pr:YLF) laser is constructed in a typical V-shaped cavity structure, while the UV output is obtained through intracavity frequency doubling using (LBO). We investigate the dependence of the UV output power, as well as the spot profile on the LBO length, and find that the "walk-off" within LBO severely affects both the frequency-doubling efficiency and the beam quality of the UV output.

Ultra-short pulse burst laser around 1.98 µm obtained through an all-fiber nonlinear wavelength converter and Tm-doped fiber amplifier.

We report an all-fiber ultra-short pulse burst laser operating at around 1.98 µm that is obtained through a nonlinear wavelength converter and Tm-doped fiber amplifier. A mode-locked Er-doped fiber laser was first built and then amplified in subsequent amplifiers to an average power of 1.

Coded-pulse-bunch-laser-based single-photon lidar for fast long-distance ranging.

Laser ranging based on a single-photon avalanche diode (SPAD), offering single-photon level high sensitivity, has been widely adopted in light detection and ranging (lidar) systems for long-distance ranging and imaging applications. Count detection through multiple pulses is commonly used when considering the existence of dark counting and strong background counting during the daytime, which improves the signal-to-noise ratio but at the expense of low detection speed. Here, we report a novel coded-pulse-bunch-laser-based single-photon lidar system, which aims to improve the ranging speed greatly and to expand the unambiguous distance to several kilometers.

Acousto-optic frequency shifted comb laser-based micro-Doppler detection for moving target identification.

We present a preliminary experimental demonstration of an acousto-optic frequency shifted (AOFS) comb laser-based micro-Doppler detection system for moving object identification. The AOFS comb laser was constructed by successively frequency shifting a single-frequency seed laser at 1063.8 nm using an acousto-optic modulator in an amplified fiber loop, which resulted in a stable pulse output with a pulse repetition rate around 150 MHz and pulse duration of about 200 ps.

High energy mid-infrared laser pulse output from a BaGaSe crystal-based optical parametric oscillator.

We report a high energy, narrow spectral linewidth mid-infrared laser pulse output from a : laser-pumped (BGSe) crystal-based optical parametric oscillator (OPO). Output pulse energy of 21.5 mJ was obtained at 3816 nm, with spectral width of 12 nm and pulse width of 11.

Improved algorithm of non-line-of-sight imaging based on the Bayesian statistics.

The recovery of obscured objects is an important goal in imaging that has been approached by exploiting coherence properties, ballistic photons, and penetrating wavelengths. In this paper, a robust reconstruction non-line-of-sight (NLOS) algorithm was proposed based on the Bayesian statistics, using the temporal, spatial, and intensity information of each signal. Compared with conventional back-projection methods, this algorithm is able to handle random errors in data and to image occluded objects with a higher quality.

Optofluidic tunable mode-locked fiber laser using a long-period grating integrated microfluidic chip.

An optofluidic tunable mode-locked fiber laser using a microfluidic chip integrated with long-period grating (LPG) is presented. The microfluidic chip enables ultrafine adjustment of the liquid's refractive index and, thus, LPG's spectrum via tuning the mixing ratio of the microfluidic flows. With such an optofluidic spectrum-tunable filter, the central wavelength of the mode-locked laser can be tuned continuously, while the mode-locking state is steadily maintained.

Watt-level mid-infrared radiation via self-seeded difference-frequency generation from a pre-chirp managed femtosecond Yb-fiber amplifier.

We obtained over 1 W average power at ∼3550  nm wavelength via self-seeded difference-frequency generation (DFG) through a 5 cm long periodically poled MgO-doped lithium niobate crystal. The pump and signal sources are derived from the identical pre-chirp managed femtosecond Yb-fiber amplifier with sub-100-fs pulse duration and 84 MHz repetition rate for simple synchronization. This result is believed to be among the highest-average-power, femtosecond mid-infrared radiation obtained via DFG.

Tunable scalar solitons from a polarization-maintaining mode-locked fiber laser using carbon nanotube and chirped fiber Bragg grating.

Generation of tunable scalar solitons from a polarization-maintaining (PM) mode-locked fiber laser is presented. A single-walled carbon nanotube (SWCNT) absorber is used for self-started mode locking. A chirped fiber Bragg grating (CFBG) mounted on a cantilever is employed as a tunable all-fiber filter.

Broadband high-power mid-IR femtosecond pulse generation from an ytterbium-doped fiber laser pumped optical parametric amplifier.

We report on a high-power periodically poled MgO-doped lithium niobate (MgO:PPLN)-based femtosecond optical parametric amplifier (OPA), featuring a spectral seamless broadband mid-infrared (MIR) output. By modifying the initial chirp and spectrum of the mode-locked seed laser, the Yb fiber pump laser exhibits a final output power of 14 W with sub-200-fs pulse duration after power amplification and compression. When the OPA was seeded with a broadband amplified spontaneous emission (ASE) source, a damage-limited 0.

Compact high power mid-infrared optical parametric oscillator pumped by a gain-switched fiber laser with "figure-of-h" pulse shape.

We demonstrate a compact high power mid-infrared (MIR) optical parametric oscillator (OPO) pumped by a gain-switched linearly polarized, pulsed fiber laser. The gain-switched fiber laser was constructed with a piece of Yb doped polarization maintaining (PM) fiber, a pair of fiber Bragg gratings written into the matched passive PM fiber and 6 pigtailed pump laser diodes working at 915 nm with 30 W output peak power each. By modulating the pulse width of the pump laser diode, simple pedestal-free pulse shape or pedestal-free trailing pulse shape ("figure-of-h" as we call it) could be achieved from the gain-switched fiber laser.

Temperature insensitive, high-power cascaded optical parametric oscillator based on an aperiodically poled lithium niobate crystal.

We report a novel temperature insensitive, APMgLN-based, high-power cascaded optical parametric oscillator (OPO) pumped by an Ytterbium-doped fiber laser. A monolithic APMgLN crystal was designed to compensate the phase mismatches for the nonlinear conversions from the pump to the idler and the primary signal to the idler simultaneously in a wide temperature range. Efficient parametric conversion with pump-to-idler conversion efficiency over 15% and slope efficiency higher than 20% was realized from 25 °C to 55 °C.

Fiber laser pumped high power mid-infrared laser with picosecond pulse bunch output.

We report a novel quasi-synchronously pumped PPMgLN-based high power mid-infrared (MIR) laser with picosecond pulse bunch output. The pump laser is a linearly polarized MOPA structured all fiberized Yb fiber laser with picosecond pulse bunch output. The output from a mode-locked seed fiber laser was directed to pass through a FBG reflector via a circulator to narrow the pulse duration from 800 ps to less than 50 ps and the spectral FWHM from 9 nm to 0.

High-power PPMgLN-based optical parametric oscillator pumped by a linearly polarized, semi-fiber-coupled acousto-optic Q-switched fiber master oscillator power amplifier.

We have experimentally demonstrated a periodically poled magnesium-oxide-doped lithium niobate (PPMgLN)-based, fiber-laser-pumped optical parametric oscillator (OPO) generating idler wavelength of 3.82 μm. The pump fiber laser was constructed with a linearly polarized, semi-fiber-coupled acousto-optic Q-switched fiber oscillator and a polarization-maintaining fiber amplifier with pulse duration of 190 ns at the highest output power.

High-power multichannel PPMgLN-based optical parametric oscillator pumped by a master oscillation power amplification-structured Q-switched fiber laser.

We experimentally demonstrated a compact fiber laser-pumped multichannel PPMgLN-based optical parametric oscillator (OPO) generating total OPO output power of 15.8, 15.2, 14.

Large aperture PPMgLN based high-power optical parametric oscillator at 3.8 µm pumped by a nanosecond linearly polarized fiber MOPA.

We report a large aperture PPMgLN based OPO generating 21W of average output power at a slope efficiency of 45%. The OPO is pumped with the output from a polarization maintaining Ytterbium doped fiber MOPA operating at 1060nm producing 20ns pulses at a repetition rate of 100kHz and an average output power of 58W (after the isolators). A maximum of 5.

Efficient parametric conversion from 1.06 to 3.8 μm by an aperiodically poled cascaded lithium niobate.

We experimentally demonstrated an efficient optical parametric oscillator (OPO) with high parametric conversion from 1.0645 to 3.8 μm.

High-efficiency semi-external-cavity-structured periodically poled MgLN-based optical parametric oscillator with output power exceeding 9.2 W at 3.82 microm.

We report a high-efficiency and high-power mid-IR laser generation by a periodically poled (PP) MgLN-based optical parametric oscillator (OPO) working at room temperature, from which 9.23 W of output was obtained at 3.82 microm when pumped by a linearly polarized acousto-optic Q-switched Nd:YVO(4) laser of 48.

Compact dual-wavelength Nd:GdVO4 laser working at 1063 and 1065 nm.

We report a compact diode-laser pumped Nd:GdVO(4) laser with stable dual-wavelength output at 1063 nm and 1065 nm simultaneously. Two types of resonant cavity configurations were presented to support the stable dual-wavelength operation of the laser. Using a polarization beam splitter(PBS) included T-shaped cavity, we obtained a total power output over 5 W in two orthogonal polarized beam directions with 4 W in sigma polarization (1065.

Short cavity single frequency fiber laser for in-situ sensing applications over a wide temperature range.

A novel Er-doped silica fiber, with heavy Er doping, was specially developed for application to a single frequency fiber laser. Two high temperature-sustainable fiber Bragg gratings, written into Bi-Ge codoped photosensitive fiber, were chosen for the application and spliced to the specialist Er doped silica fiber to form a compact, linear cavity, fiber laser. The fiber laser retained single mode oscillation over a wide temperature range, from room temperature to 400 degrees C.

Photonic nanowires directly drawn from bulk glasses.

High-uniform nanowires with diameters down to 50 nm are directly taper-drawn from bulk glasses. Typical loss of these wires goes down to 0.1 dB/mm for single-mode operation.

High-temperature sustainability of strong fiber Bragg gratings written into Sb-Ge-codoped photosensitive fiber: decay mechanisms involved during annealing.

An antimony--germanium- (Sb--Ge-) codoped fiber specially designed for the fabrication of fiber Bragg gratings (FBGs) with high temperature sustainability has been developed. The photosensitivity and the high-temperature sustainability of FBGs that have been written into this fiber were tested. The results obtained showed that the FBG written into this fiber has a very high temperature sustainability of 900 degrees C.

Highly photosensitive Sb/Er/Ge-codoped silica fiber for writing fiber Bragg gratings with strong high-temperature sustainability.

A highly photosensitive Sb/Er/Ge-codoped silica fiber for fabricating fiber Bragg gratings (FBGs) with strong high-temperature sustainability is presented. The photosensitivity and the high-temperature sustainability of FBGs created in this fiber are examined and compared with those produced in a Sn-doped silica fiber. The results show that the Sb/Er/Ge fiber has a much higher level of photosensitivity than the Sn-doped silica fiber and that the FBGs have a similar high-temperature sustainability of 800 degrees C.