A review of the Japanese Cryptochironomus Kieffer, 1918 (Diptera, Chironomidae).

The genus Cryptochironomus Kieffer, 1918 from Japan is reviewed based on material composed of male adults. New combinations of three species are established and they are re-described based on male adult of: C. misumaiprimus (Sasa & Suzuki, 1998), comb. n., C. tokaraefeus (Sasa & Suzuki, 1995), comb. n. and C. tonewabeus (Sasa & Tanaka, 2002), comb. n. Additional taxonomic notes are also provided: C. albofasciatus (Staeger, 1839), which is a senior synonym of Parachironomus inafegeus Sasa, Kitami & Suzuki, 2001 and C. rostratus (Kieffer, 1921) as the senior synonym of Paracladopelma inaheia Sasa, Kitami & Suzuki, 2001. A key to the known adult males of the genus from Japan is given.

Two new and one newly recorded species of Polypedilum Kieffer 1912 with DNA barcodes from Oriental China (Chironomidae: Diptera).

Polypedilum (Tripodura) enshiense Song & Wang sp. n. and P. (Tripodura) jianfengense Song & Wang sp. n. are described and illustrated as male imagines from China. P. (Uresipedilum) paraconvictum Yamamoto, Yamamoto & Hirowatari, 2016 is recorded from China for the first time. Cytochrome coxidase subunit I (COI) sequence of above species are uploaded to Barcode of Life Data Systems (BOLD).

A new record and two new species of Cryptochironomus Kieffer, 1918 from China (Diptera, Chironomidae).

Two new species of the genus Cryptochironomus Kieffer, C. maculus Yan & Wang sp. n. and C. protuberans Yan & Wang sp. n. are described and illustrated as adult males. C. albofasciatus (Staeger) is recorded from China for the first time. A key to the males of Cryptochironomus in China is presented and generic diagnosis is emended.

Segmenting Brain Tissues from Chinese Visible Human Dataset by Deep-Learned Features with Stacked Autoencoder.

Cryosection brain images in Chinese Visible Human (CVH) dataset contain rich anatomical structure information of tissues because of its high resolution (e.g., 0.167 mm per pixel). Fast and accurate segmentation of these images into white matter, gray matter, and cerebrospinal fluid plays a critical role in analyzing and measuring the anatomical structures of human brain. However, most existing automated segmentation methods are designed for computed tomography or magnetic resonance imaging data, and they may not be applicable for cryosection images due to the imaging difference. In this paper, we propose a supervised learning-based CVH brain tissues segmentation method that uses stacked autoencoder (SAE) to automatically learn the deep feature representations. Specifically, our model includes two successive parts where two three-layer SAEs take image patches as input to learn the complex anatomical feature representation, and then these features are sent to Softmax classifier for inferring the labels. Experimental results validated the effectiveness of our method and showed that it outperformed four other classical brain tissue detection strategies. Furthermore, we reconstructed three-dimensional surfaces of these tissues, which show their potential in exploring the high-resolution anatomical structures of human brain.

High efficient actively Q-switched Ho:LuAG laser.

We present the room temperature Q-switched performances of a Ho:LuAG laser operated at 2.1 microm. At the repetition rate of 10 kHz, the maximum average output power of 9.9 W with a slope efficiency of 69.9% relative to absorbed pump power was obtained in Ho:LuAG laser. Also, the minimum pulse width of 33.0 ns was obtained, corresponding to the peak power was 30.0 kW.

Continuous-wave laser action around 2-microm in Ho3+:Lu2SiO5.

Continuous-wave (cw) laser action around 2 microm in Ho(3+)-doped Lu(2)SiO(5) (LSO) was demonstrated in this paper. Cryogenically cooled by liquid nitrogen, a 10-mm long Tm-sensitized (6% at.) Ho(0.4% at.):LSO produced a maximum output power of 3 W at 2.07 microm for incident diode power of 11 W at 786 nm, and a slope efficiency of 35% with respect to incident pump power. To achieve room-temperature operation of Tm, Ho:LSO laser, a 1-mm long microchip crystal was pumped by a high brightness diode, generating an output power of greater than 80 mW and a slope efficiency of 26% at 2.08 microm. Using a 1.91 microm Tm:YLF laser as an in-band pump source, room-temperature cw operation of singly-doped Ho: Lu(2)SiO(5) laser at 2106 nm was attained with a maximum output power of 2.8 W and a slope efficiency of 35% corresponding to absorbed pump power.

Room temperature efficient actively Q-switched Ho:YAP laser.

We report on efficient actively Q-switched Ho:YAP laser double-pass pumped by a 1.91-microm laser. At room temperature, when the incident pump power was 20.9 W, a maximum average output power of 10.9 W at 2118 nm was obtained at the repetition rate of 10 kHz, and this corresponds to a conversion efficiency of 52.2% and a slope efficiency of 63.5%. Moreover, a maximum pulse energy of approximately 1.1 mJ and a minimum pulse width of 31 ns were achieved, with the peak power of 35.5 kW.

7.3 W of single-frequency output power at 2.09 mum from an Ho:YAG monolithic nonplanar ring laser.

Single-frequency output power of 7.3 W at 2.09 mum from a monolithic Ho:YAG nonplanar ring oscillator (NPRO) is demonstrated. Resonantly pumped by a Tm-doped fiber laser at 1.91 mum, the Ho:YAG NPRO produces 71% of slope efficiency with respect to absorbed pump power and nearly diffraction-limited output with a beam quality parameter of M(2) approximately 1.1.

Continuous-wave and Q-switched operation of a resonantly pumped Ho:YAlO3 laser.

We demonstrated continuous-wave (CW) and Q-switched operation of a room-temperature Ho:YAlO(3) laser that is resonantly end-pumped by a diode-pumped Tm:YLF laser at 1.91 microm. The CW Ho:YAlO(3) laser generated 5.5 W of linearly polarized (EII c ) output at 2118 nm with beam quality factor of M(2) approximately 1.1 for an incident pump power of 13.8 W, corresponding to optical-to-optical conversion efficiency of 40%. Up to 1- mJ energy per pulse at pulse repetition frequency (PRF) of 5 kHz, and the maximum average power of 5.3-W with FWHM pulse duration of 30.5 ns at 20 kHz were achieved in Q-switched mode.

Diode-pumped continuous wave and Q-switched operation of a c-cut Tm,Ho:YAlO(3) laser.

We report on a diode-pumped, cryogenic and room temperature operation of a Tm,Ho:YAlO3 (c-cut) laser. In a temperature of 77 K, an optical-optical conversion efficiency of 27% and a slope efficiency of 29% were achieved with the maximum continuous-wave (CW) output power of 5.0 W at 2.13 microm. Acousto-optic switched operation was performed at pulse repetition frequency (PRF) from 1 kHz to 10 kHz, the highest pulse energy of 3.3 mJ in a pulse duration of 40 ns was obtained. In room temperature (RT), the maximum CW power of Tm,Ho:YAlO3 laser was 160 mW with a slope efficiency of 11% corresponding to the absorbed pump power.

Effects of gamma-irradiation and air annealing on Yb-doped Y3Al5O12 single crystal.

The effects of gamma-irradiation on the air-annealed 10at.% Yb:Y(3)Al(5)O(12) (YAG) and air annealing on the gamma-irradiated 10at.% Yb:YAG have been studied by the difference absorption spectra before and after treatment. The gamma-irradiation and air annealing led to opposite changes of the absorption properties of the Yb:YAG crystal. After air annealing, the gamma-irradiation induced centers were totally removed and the concentration of Fe(3+) and Yb(3+) were lightly increased. For the first time, the gamma-irradiation induced valence changes between Yb(3+) and Yb(2+) ions in Yb:YAG crystals have been observed.

Diode-pumped Yb:GSO femtosecond laser.

Compact femtosecond laser operation of Yb:Gd(2)SiO(5) (Yb:GSO) crystal was demonstrated under high-brightness diode-end-pumping. A semiconductor saturable absorption mirror was used to start passive mode-locking. Stable mode-locking could be realized near the emission bands around 1031, 1048, and 1088 nm, respectively. The mode-locked Yb:GSO laser could be tuned from one stable mode-locking band to another with adjustable pulse durations in the range 1~100 ps by slightly aligning laser cavity to allow laser oscillations at different central wavelengths. A pair of SF10 prisms was inserted into the laser cavity to compensate for the group velocity dispersion. The mode-locked pulses centered at 1031 nm were compressed to 343 fs under a typical operation situation with a maximum output power of 396 mW.

Passively Q-switched Yb(3+) laser with Yb(3+)-doped CaF(2) crystal as saturable absorber.

Passive Q-switching of a diode-pumped Yb:LYSO laser at 1060 nm with a Yb(3+) ions-doped CaF(2) crystal without the excited-state absorption (ESA) was demonstrated. An average output power of 174 mW with pulse duration of 5.6 mus and repetition rate of 27 kHz have been obtained under the unoptimized conditions. And the Q-switching conversion efficiency was as high as 51.7%.

Group delay dispersion measurement of Yb:Gd(2)SiO(5), Yb:GdYSiO(5) and Yb:LuYSiO(5)crystal with white-light interferometry.

We report the measured group delay dispersion (GDD) of new crystals Yb:Gd(2)SiO,(5)(Yb:GSO), Yb:GdYSiO(5) (Yb:GYSO) and Yb:LuYSiO(5) (Yb:LYSO) over wavelengths from 1000nm to 1200nm, with a white-light interferometer. Those GDD data should be useful for the dispersion compensation for femtosecond pulse generation in the lasers with these new crystals as the gain media.

Simultaneous three-photon-excited violet upconversion luminescence of Ce3+:Lu2Si2O7 single crystals by femtosecond laser irradiation.

We found that Ce3+:Lu2Si2O7 single crystals could be excited at 800 nm by using a femtosecond Ti:sapphire laser. The emission spectra of Ce3+:Lu2Si2O7 crystals were the same for one-photon excitation at 267 nm as for excitation at 800 nm. The emission intensity of Ce3+:Lu2Si2O7 crystals was found to depend on the cube of the laser power at 800 nm, consistent with simultaneous absorption of three 800 nm photons. The measured value of the three-photon absorption cross section is sigma'3=2.44x10(-77) cm6 s2.

Effects of Yb concentration on the fluorescence spectra of Yb-doped YAlO3 single crystals.

0.5 at.% Yb:YAlO(3)(YAP), 5 at.% Yb:YAP and 15 at.% Yb:YAP were grown using the Czochralski method. Their absorption and fluorescence spectra were measured at room temperature and their emission line shape was calculated using the method of reciprocity. It was observed that the fluorescence spectra changed appreciably with the increasing of Yb concentration. For 0.5 at.% Yb:YAP, the line shape of fluorescence is very similar with the calculated emission line shape; with the increasing of Yb doping concentration, the line shape of fluorescence is very different from the calculated emission line shape. These phenomena are caused by the strong self-absorption at 979 and 999 nm for Yb:YAP.

Three-photon-excited upconversion luminescence of Ce(3+): YAP crystal by femtosecond laser irradiation.

Infrared to ultraviolet and visible upconversion luminescence was demonstrated in trivalent cerium doped YAlO(3) crystal (Ce(3+): YAP) under focused infrared femtosecond laser irradiation. The fluorescence spectra show that the upconverted luminescence comes from the 5d-4f transitions of trivalent cerium ions. The dependence of luminescence intensity of trivalent cerium on infrared pumping power reveals that the conversion of infrared radiation is dominated by three-photon excitation process. It is suggested that the simultaneous absorption of three infrared photons pumps the Ce(3+) ion into upper 5d level, which quickly nonradiatively relax to lowest 5d level. Thereafter, the ions radiatively return to the ground states, leading to the characteristic emission of Ce(3+).

Diode-pumped continuous-wave and passively mode-locked Yb:GSO laser.

We report on both continuous-wave and passively mode-locked laser actions of a new ytterbium-doped laser crystal Yb:Gd(2)SiO(5) (Yb:GSO) under high-power diode-end-pumping. Due to the anisotropic and compact crystal structure, Yb:GSO exhibits a large manifold splitting of Yb(3+) ions, and a Yb:GSO laser can be operated efficiently with negligible reabsorption losses at emission wavelengths. In the continuous-wave operation, a Yb:GSO laser was operated with a slope efficiency of 49% near 1094 nm--the longest laser wavelength achieved for Yb(3+) lasers. Passive mode locking was obtained with a semiconductor saturable-absorber mirror. At a pump power of 6.23 W, a maximum average output power of 638 mW was obtained with the repetition rate of 145.5 MHz.

Blue upconversion luminescence generation in Ce3+:Gd2SiO5 crystals by infrared femtosecond laser irradiation.

Blue frequency-upconversion fluorescence emission has been observed in Ce(3+)-doped Gd(2)SiO(5) single crystals, pumped with 120-fs 800 nm IR laser pulses. The observed fluorescence emission peaks at about 440nm is due to 5d?4f transition of Ce3+ ions. The intensity dependence of the blue fluorescence emission on the IR excitation laser power obeys the cubic law, demonstrating three-photon absorption process. Analysis suggested that three-photon simultaneous absorption induced population inversion should be the predominant frequency upconversion mechanism.

Tunable and efficient diode-pumped Yb3+:GYSO laser.

Effective diode-pumped cw tunable laser action of a new alloyed crystal Yb:Gd(2(1-x))Y(2x)SiO(5) (Yb:GYSO, x = 0.5) is demonstrated for the first time. The alloyed crystal retains excellent laser properties of Gd(2)SiO(5) (GSO), as well as the favorable growth properties and the desirable physical of Y(2)SiO(5) (YSO). With a 5-at.% Yb:GYSO sample, we achieved 2.44 W output power at 1081.5 nm and a slope efficiency of 57%. And its laser wavelength could be tuned from 1030nm to 1089 nm.