ABSTRACT
We demonstrate the generation of an ultra-widely tunable mid-infrared (6-18 µm) optical vortex output with a moderate pulse energy from a AgGaSe2 difference frequency generator pumped by an optical vortex parametric oscillator. The handedness of the vortex output can be controlled/selected by swapping the lasing frequencies of the signal and idler outputs and rotating the AgGaSe2 crystal by 90 deg.
ABSTRACT
We demonstrate a tunable vortex laser with versatile orbital angular momentum (OAM) states based on a singly resonant optical parametric oscillator formed of a noncritical phase-matching LiB3O5 crystal. The selective generation of a signal (idler) output with three OAMs, including an upconverted (negative) OAM, is achieved simply by appropriate shortening (or extending) of the cavity. The compact cavity configuration also allows for the generation of the signal (idler) output with various OAMs by simply tuning the signal wavelength. The vortex output is tuned within the wavelength region of 0.74 to 1.84 µm with a maximum pulse energy of 2.16 mJ from a pump energy of 9.3 mJ.
ABSTRACT
Frequency doubling of optical vortices is demonstrated with an optical-optical efficiency exceeding 70%, using a spiral phase plate at a fundamental vortex energy of 10.6 mJ. Beam propagation of the doubled vortex output is also investigated both experimentally and theoretically. Spatial transforms in the output during propagation are observed.
ABSTRACT
We developed an octave-band tunable optical vortex laser based on a 532 nm optical vortex pumped optical parametric oscillator with a simple linear-cavity configuration by employing cascaded non-critical phase-matching LiB3O5 crystals. The optical vortex output was tunable from 735 to 1903 nm. For a pump energy of 9 mJ, an optical vortex pulse energy of 0.24-2.36 mJ was obtained, corresponding to an optical-optical efficiency of 0.3-26%.
ABSTRACT
The flower bud transcriptome in the less dormant Taiwanese pear 'Hengshanli' and high-chilling requiring Japanese pear strain TH3 subjected to the same chilling exposure time were analyzed during winter using next-generation sequencing. In buds sampled on January 10th and on February 7th in 2014, 6,978 and 7,096 genes, respectively, were significantly differentially expressed in the TH3 and 'Hengshanli' libraries. A comparative GO analysis revealed that oxidation-reduction process (biological process) and ATP binding (molecular function), were overrepresented during the ecodormancy period (EP) when compared to the endodormancy deepest period (DP), indicating that ATP synthesis was activated during the transition between these dormancy stages. Among the 11 differently expressed genes (DEGs) annotated as probable dehydrins or LEA protein-related genes, 9 DEGs showed higher transcript levels in the DP than in the EP. In order to focus on transcription factors induced by low temperature or drought, 7 differently expressed genes (DEGs) annotated as probable ICE1 or DREB proteins were analyzed by real-time PCR. Expression levels of 3 genes were higher in TH3 than in 'Hengshanli' on all sampling days. Their expression increased during the endodormancy deepest period (DP) and then decreased before endodormancy breaking in TH3 buds. Taken together, these results suggest that these genes annotated as ICE1, DREB and ERF are involved in endodormancy maintenance and in the transition from endodormancy to ecodormancy.
Subject(s)
Gene Expression Regulation, Plant , Plant Dormancy , Pyrus/growth & development , Pyrus/genetics , Gene Expression Profiling , Plant Proteins/genetics , Seasons , Taiwan , TranscriptomeABSTRACT
We demonstrate an all-fiber Q-switched laser operation in the 2 µm region on the basis of a dynamic periodic microbend and pulsed-pump configuration. A single-mode thulium-doped silica fiber is pumped by 1.6 µm-band laser diodes, and the dynamic loss is introduced in the fiber ring resonator by the periodic microbend that is electrically controlled with a piezoelectric actuator. When the voltage-off period of the piezoelectric actuator is set at 20 µs for the pump power of 120 mW, the output pulse power is measured by 420 mW with a pulse width of 1.3 µs.
