Tm:YAG ceramic derived multimaterial fiber with high gain per unit length for 2 µm laser applications.

In this work, Tm:YAG (Tm:${{\rm Y}_3}{{\rm Al}_5}{{\rm O}_{12}}$Y3Al5O12) ceramic-derived multimaterial fiber was fabricated by using the molten core method, which has a high gain per unit length of 2.7 dB/cm at 1950 nm. To our knowledge, this is the highest gain per unit length at 2 µm band in similar Tm:YAG-derived multimaterial fibers. A distributed Bragg reflector (DBR) fiber laser was built based on a 10-cm-long as-drawn fiber. The achieved 1950 nm laser, which has a maximum output power of $\sim{240}\;{\rm mW}$∼240mW and a slope efficiency of 16.5%, was pumped by a self-developed 1610 nm fiber laser. What is more, an all-fiber-integrated passively mode-locked fiber laser based on the 10-cm-long as-drawn fiber was realized. The mode-locked pulses operate at 1950 nm with duration of $\sim{380}\;{\rm ps}$∼380ps, and the repetition rate is 26.45 MHz. The results described here indicate that the Tm:YAG ceramic-derived multimaterial fiber with high gain per unit length has promising applications in 2 µm all-fiber fiber lasers.

Broadband 2 µm amplified spontaneous emission of Ho/Cr/Tm:YAG crystal derived all-glass fibers for mode-locked fiber laser applications.

Broadband ∼2 µm amplified spontaneous emissions with a full width at half-maximum (FWHM) varying from ∼206 to ∼234 nm were obtained from the Ho/Cr/Tm:yttrium aluminum garnet (YAG) crystal derived fibers, which were drawn using a molten core method. The core-cladding structure of the as-drawn fibers was preserved completely, and the core was found to be amorphous. What is more, an all-fiber-integrated passively mode-locked laser based on an 8 cm long Ho/Cr/Tm:YAG crystal derived all-glass fiber was built which, to the best of our knowledge, is the first demonstration of a mode-locked fiber laser in a similar YAG derived fiber. The mode-locked pulses operate at 1.95 µm with duration of ∼118 ps, and the repetition rate is ∼9.5 MHz. Limited by the bandwidth of the fiber grating used in the laser cavity, the mode-locking spectrum has a relatively narrow FWHM of ∼0.09 nm. These results suggest that the broadband YAG crystal derived all-glass fibers are promising for ultrafast fiber lasers applications.

High-efficiency sub-watt in-band-pumped single-frequency DBR Tm3+-doped germanate fiber laser at 1950 nm.

Based on a 1.8-cm-long heavily Tm3+-doped germanate fiber and being in-band-pumped by a 1610 nm single-mode laser, a high-efficiency and high-power single-frequency distribute Bragg reflector (DBR) fiber laser emitting at 1950 nm is demonstrated. The DBR fiber laser has a maximum output power of ~617 mW and a slope efficiency for the absorbed pump power reaches to more than 42.2%. A stable single-longitudinal-mode laser output with a signal-to-noise ratio of greater than 63 dB is realized. The measured relative intensity-noise of the fiber laser reaches to around -150 dB/Hz at frequencies of over 8.4 MHz. It is beneficial to exploit the sub-watt and high-efficiency single-frequency laser from fiber oscillators directly, especially in the application of multiple paths coherent beam combination and optical medical technology.

[Association of T190C polymorphism of ß3 adrenergic receptor gene with response to carvedilol in patients with chronic heart failure].

OBJECTIVE: To assess the association of T190C polymorphism of ß3 adrenergic receptor gene (ß3-AR) with chronic heart failure (CHF), and to evaluate the effect of this polymorphism on clinical response to ß-AR blockade among patients with CHF. METHODS: Three hundred and thirty patients with stable CHF receiving basic therapy for heart failure were included. Before initiation and 5 months after the maximal tolerated dose of carvedilol was reached, all indices including heart rate (HR), blood pressure (BP), left atrial diameter (LAD), left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), left ventricular ejection fraction (LVEF), brain natriuretic peptide (BNP) level, 6 min walk distance were measured and compared with the indices of those with a T190C genotype. Distribution of the T190C polymorphisms in the control group and CHF group was compared. RESULTS: The frequencies of T190C genotypes of the ß3-AR gene have fit with the Hardy-Weinberg equilibrium. No significant difference was found between the frequencies of T190C alleles and genotypes between the two groups (P > 0.05). Compared with CC-homozygotes, TT-homozygous patients showed substantially greater improvement in LVEF and BNP (all P < 0.01). CONCLUSION: No difference has been detected in the prevalence of the three genotypes between healthy and CHF subjects. The T190C variation of the ß3-AR gene was not associated with increased risk for CHF. CHF patients with a T allele have greater response to carvedilol than those carrying a C allele in ethnic Han Chinese.