Search

Purpose: Vasostatin 48 (VS48) is a peptide of 48 amino acids derived from calreticulin. This study aimed to investigate the effects of topical application of VS48 eyedrops on experimental choroidal neovascularization (CNV)., Methods: Recombinant VS48 was expressed and purified as a thioredoxin (TRX)-fused protein, TRX-VS48. The anti-angiogenic effects of TRX-VS48 were validated by migration and tube formation assays performed on cultured endothelial cells, and by rat aorta ring assays. CNV lesions were created in Brown Norway rats by laser-induced photocoagulation at day 1. After topical TRX-VS48 application for 21 days, the CNV lesions were monitored via either choroidal flat mounts on day 21 or by fluorescent angiography on days 21, 28, 35, and 42. CNV lesions were evaluated by histological analysis. The retinal function of animals was examined by electroretinogram (ERG) to evaluate the safety and therapeutic efficacy of TRX-VS48., Results: Application of TRX-VS48 inhibited the migration and tube formation of endothelial cells. TRX-VS48 inhibited the growth of sprouting vessels in aorta rings. ERG analysis revealed that topical TRX-VS48 application for 21 days had no effect on rat retinal functions. After CNV induction, topical TRX-VS48 application for 21 days significantly reduced the size of CNV, as assayed by flat mounts. Fluorescent angiography revealed that the CNV areas in TRX-VS48-treated eyes were significantly reduced compared with TRX-treated eyes on days 21, 28, 35, and 42. Histological analysis also revealed attenuated CNV lesions in TRX-VS48-treated eyes. Topical TRX-VS48 treatment significantly reversed the CNV-induced alterations in ERG parameters on day 35., Conclusions: Topical TRX-VS48 application suppressed laser-induced CNV in rats, thereby constituting a possible modality for ocular diseases due to excessive angiogenesis.

Intra-cavity pumped Ho laser basing on the biaxial YAP host is investigated here for a direct LD pumped compact polarized 2.1 μm laser at room temperature, where the a-cut and b-cut Tm:YAP and Ho:YAP crystals were applied and placed with the same crystallographic orientation. The maximum output power of 2.47 W at 2118 nm was obtained for the b-cut Ho:YAP laser with a slope efficiency of 15.1%, which is higher than that of 1.08 W at 2130 nm for the a-cut Ho:YAP laser with a slope efficiency of 8.9%, attributed to the better spectral overlap between the intra-cavity Tm laser and polarized absorption profile of the Ho:YAP crystal. Scaling up the output power and slope efficiency of the current Ho:YAP laser is predictable via improving heat management of the current structure further by diffusion bonding the Tm:YAP crystal with another un-doped YAP crystal or using a slab Tm:YAP crystal structure for rapid heat transfer. [ABSTRACT FROM AUTHOR]

We demonstrate electro-optical Q-switching in a direct 792 nm diode-pumped composite Tm/Ho:YLF laser. Spectral analyses on Tm:YLF and Ho:YLF crystals were studied in detail. A coupled cavity consisting of two identical bi-concave sub-cavities was developed for polarization separation and ensuring rigorous mode-matching between the σ -polarized Tm:YLF and π -polarized Ho:YLF lasers intra-cavity. Together with the negative thermal-optical coefficient with weak thermal lensing of the fluoride host, near diffraction limited Q-switched Ho laser with maximum average power of 389 mW and peak power of 3.3 kW at 2051 nm were obtained at pulse repetition rates of 5 kHz and 1 kHz respectively, which benefits a compact, accessible pulsed seed source at 2. 1 μ m. • We firstly demonstrate electro-optical Q-switching in a composite Tm/Ho:YLF laser. • Novel coupled cavity was proposed for sepearting the σ -pol Tm laser and π -pol Ho laser intra-cavity. • Near diffraction limited pulsed Ho laser was obtained with maximum average power of 389 mW at 2051 nm. [ABSTRACT FROM AUTHOR]

• We demonstrate an electro-optically Q-switched Tm laser with constant short pulse duration of sub-25 ns at high PRFs ranging from 75 kHz to 150 kHz. • Maximum power of 22.4 W at 1936.8 nm is obtained at 75 kHz, with average duration of 21 ns and a deviation below 0.8 ns, corresponding to a peak power of 14.2 kW. • The results provide an efficient way to achieve constant short nanosecond pulse in high-power Q-switched Tm lasers. Conventionally, pulse duration of Q-switched lasers changes dynamically with the lasing power and pulse repetition frequency (PRF). Especially in quasi-three level Tm lasers, owing to the small emission cross section, they should oscillate at a PRF of below 50 kHz for a short Q-switching pulse that generally limited at tens of nanosecond. In this paper, we demonstrate an unprecedented electro-optically Q-switching scheme with constant short pulse duration of sub-25 ns at high PRFs ranging from 75 kHz to 150 kHz. Maximum average output power of 22.4 W at 1936.8 nm is obtained at 75 kHz, where average pulse duration of 21 ns with a deviation below 0.8 ns is realized during the whole Q-switching process, corresponding to a maximum peak power of 14.2 kW. The results provide an efficient way to achieve constant short nanosecond pulse in the high-power Q-switched Tm lasers, which could work at a PRF of above 100 kHz and facilitate a variety of appealing applications in material processing, surgery, and nonlinear frequency conversion toward the mid- and far-infrared regions. [ABSTRACT FROM AUTHOR]

• A robust 2-μm wavelength-switchable Tm/Ho composite laser was demonstrated. • In Tm laser, maximum CW power of 1.12 W and peak power of 1.36 kW were obtained. • In Ho laser, maximum CW power of 1.04 W and peak power of 186 W were obtained. We demonstrated a 2-μm wavelength-switchable Tm/Ho composite laser employing a compact hybrid cavity with changeable output couplers, which facilitates the direct use of common 800 nm diode lasers for separated Tm laser and Ho laser from a single bulk composite gain medium and can work in both continuous wave (CW) and Q-switching manners. With the broad band coated output couplers, maximum CW power of 1.12 W and shortest passively Q-switched (PQS) pulses with a width of 15.7 ns under a repetition frequency of 6.7 kHz were obtained in pure Tm laser at 2011 nm. With the narrow-band coated output couplers, maximum CW power of 1.04 W and shortest PQS pulse of 118 ns under repetition rate of 10.5 kHz were obtained in pure Ho laser at 2091 nm. Combing both advantages of Tm laser and Ho laser, a wide scope of applications including detection, commutation, and medical treatments are expected from the proposed laser source due to its accessibility, multifunction and miniaturization. [ABSTRACT FROM AUTHOR]

• High-power cavity-dumped Tm laser, with high repetition frequency about 100 kHz is developed with a dual-end pumped configuration. • A plano-convex lens is used to compensate severe thermal lens inside the Tm:YAP crystal. • Maximum output power for the cavity-dumped Tm lasers, with a value of 10.07 W at 1.94 μm is obtained with pulse duration of 26.4 ns at 110 kHz. We demonstrate a high-repetition-frequency, cavity-dumped Tm:YAP slab laser, producing short nanosecond pulse at 1.94 μm. A thermal-lens-compensated cavity with a dual-end pumping configuration is developed for high-power operation. The achieved maximum Tm laser power is 10.7 W, with a pulse width of 26.4 ns at a frequency of 110 kHz, resulting in a peak power of 3.68 kW. To the best of our knowledge, this represents the highest output power for the cavity-dumped Tm laser. The results provide a robust scheme to develop high-power, high-repetition-frequency diode-pumped 2 μm lasers with a constant sub-50 ns pulse duration, opening avenues for versatile applications including medical treatment, material processing, and nonlinear frequency conversion towards the mid-infrared region. [ABSTRACT FROM AUTHOR]

• Tm:YLF crystal, with weak thermal lens was applied for comparing lasing performances among the intra-cavity pumped Ho:YLF, Ho:YAG, and Ho:YAP lasers. • c-cut Tm:YLF laser with wavelength at 1909 nm for σ-polarization matches well with absorption bands of the aforementioned crystals for an efficient 2.1 μm laser. • Maximum powers of 8.63 w at 2063.1 nm, 7.45 W at 2122.2 nm and 3.55 W at 2129.5 nm were obtained, respectively from the Ho:YLF, Ho:YAG, and Ho:YAP lasers. We demonstrate lasing properties of the c-cut Ho:YLF, Ho:YAG and c-cut Ho:YAP laser intra-cavity pumped by a σ-polarized Tm:YLF laser within a compact linear cavity. Owing to the weak thermal lens of the YLF-based host media, maximum Ho laser power of 8.63 W at 2063.1 nm, with a slope efficiency of 25.2% and M2 of 1.41 was obtained in the Ho:YLF laser. Besides, maximum output power of 7.45 W at 2122.2 nm and 3.55 W at 2129.5 nm were obtained with the Ho:YAG and Ho:YAP lasers, respectively, with corresponding slope efficiencies of 23.1% and 11.8%. [ABSTRACT FROM AUTHOR]

• An efficient YAP-based intra-cavity pumped polarized Ho laser facilitating the direct use of common LD. • Above 10 W at 2.13 μm, the maximum power for compact intra-cavity pumped Ho lasers. • Analyzing thermal effects in stress and thermal lens with anisotropic properties of the biaxial YAP host. • Appling a composite YAP/Tm:YAP gain medium for improving heat management. We demonstrated efficient Ho:YAP laser pumped with a composite YAP/Tm:YAP laser intra-cavity, where both Tm-doped and Ho-doped YAP hosts were placed with identical crystallographic orientations. In the composite Tm laser, maximum output power of 18.42 W at 1999 nm, corresponding to a slope efficiency of 46.4% was obtained. In the Ho:YAP laser, maximum output power of 10.6 W at 2130 nm (E//b) for the compact intra-cavity pumped Ho lasers was obtained, to the best of our knowledge, corresponding to a slope efficiency of 25.7%. [ABSTRACT FROM AUTHOR]

• Tm:YVO 4 crystal is an excellent laser gain medium for 2 μm lasers due to the large absorption cross-section. • WSe 2 as one of saturable absorbers receives great attentions due to the broad-band non-linear absorption, ultra-fast recovery time, controllable modulation depth and low manufacturing cost. • Therefore, it is well-expected that the passively Q-switched Tm:YVO 4 laser with WSe 2 -SA, however, these is no relevant report yet. • In this paper, we firstly achieved PQS Tm:YVO 4 laser using few-layer WSe2-SA. • Compared with those reported in 2 μm PQS lasers using WSe 2 -SA, a higher peak power of 38 W was obtained in our experiment. • The experimental results indicate that the combination between Tm:YVO 4 crystal and WSe 2 -SA is an efficient way for a compact high power PQS 2 μm laser. In this paper, we reported a watt-level passively Q-switched Tm:YVO 4 laser using few-layer WSe 2 nanosheets as the saturable absorber. Under an absorbed pump power of 9.65 W, a maximum average output power of 1.13 W at 1925.6 nm was obtained with shortest pulse duration of 446 ns at repetition rate of 66.8 kHz, corresponding to single pulse energy of 16.9 µJ and peak power of 38 W. At the maximum average output power of the passively Q-switched Tm:YVO 4 laser, the beam quality factors (M2) in the horizontal direction and vertical direction were estimated to be 1.36 and 1.27, respectively. [ABSTRACT FROM AUTHOR]

We firstly explored lasing properties of a 2. 1 μ m Ho laser intra-cavity pumped by a diode-pumped Tm:YVO 4 laser, which has a large absorption cross-section and broad absorption profile at 800 nm. Maximum output power of 1.42 W at 1908 nm was obtained before Ho laser with a 2 mm long Tm:YVO 4 crystal under absorbed common 808 nm LD power of 9.96 W. High reflection coating the output couplers at Tm laser, Ho laser oscillation with maximum output power of 954 mW at 2122 nm was achieved with corresponding beam quality factor M2 of 1.43, which indicates a near-diffraction-limited beam propagation. • Tm:YVO 4 crystal has a larger absorption cross-section near 800 nm. • The larger absorption cross-section of Tm:YVO 4 benefits the use of the AlGaAs LDs • Maximum output power of 954 mW at 2122 nm was achieved with a 2 mm Tm:YVO 4 crystal. • Beam quality factor of 1.43 indicating a near-diffraction-limited beam propagation. [ABSTRACT FROM AUTHOR]