Peiwen Kuan

Tm 3+ and Tm 3+ -Ho 3+ co-doped tungsten tellurite glass single mode fiber laser

We investigated the ~2 μm spectroscopic and lasing performance of Tm(3+) and Tm(3+)-Ho(3+) co-doped tungsten tellurite glass single mode fibers with a commercial 800 nm laser diode. The double cladding single mode (SM) fibers were fabricated by using rod-in-tube method. The propagation loss of the fiber was ~2.5 dB/m at 1310 nm. The spectroscopic properties of the fibers were analyzed. A 494 mW laser operating at ~1.9 μm was achieved in a Tm(3+) doped 20 cm long fiber, the slope efficiency was 26%, and the laser beam quality factor M(2) was 1.09. A 35 mW ~2.1 μm laser output was also demonstrated in a 7 cm long of Tm(3+)-Ho(3+) co-doped tungsten tellurite SM fiber.

Compact broadband amplified spontaneous emission in Tm3+-doped tungsten tellurite glass double-cladding single-mode fiber.

We reported the ~2 μm amplified spontaneous emission (ASE) performance of highly Tm3+-doped (3.76 × 1020 ions/cm3) tungsten tellurite single-mode fibers. The double-cladding fiber was pumped by a commercial 792 nm laser diode without any reflectors. Broadband ASE spectra with the bandwidth (FWHM) varying from ~45 nm to ~140 nm were achieved in a fiber length of 34 cm. The maximum output power was ~34 mW, with a slope efficiency of 4.8%. The ASE beam quality factor (M2) was 1.8. The dependence of output power, ASE mean wavelength, and bandwidth on the launched pump power and fiber length were discussed in detail.

Multicolor upconversion emissions in Tm 3+ /Er 3+ codoped tellurite photonic microwire between silica fiber tapers

We report multicolor upconversion emissions including the blue-violet, green, and red lights in a Tm 3+/Er3+codoped tellurite glass photonic microwire between two silica fiber tapers. A silica fiber is tapered until its evanescent field is exposed and then angled-cleaved at the tapered center to divide the tapered fibers into two parts. A tellurite glass is melted by a gas flame to cluster into a sphere at the tip of one tapered fiber. The other angled-cleaved tapered fiber is blended into the melted tellurite glass. When the tellurite glass is melted, the two silica fiber tapers are simultaneously moving outwards to draw the tellurite glass into a microwire in between. The advantage of angled-cleaving on fiber tapers is to avoid cavity resonances in high index photonic microwire. Thus, the broadband white light can be transmitted between silica fibers and a special optical property like high intensity upconversion emission can be achieved. A cw 1064 nm Nd:YAG laser light is launched into the Tm 3+/Er3+ codoped tellurite microwire through a silica fiber taper to generate the multicolor upconversion emissions, including the blue-violet, green, and red lights, simultaneously.

Spectroscopic properties and quenching mechanism of 2 μm emission in Ho 3+ doped germanate glasses and fibers

The 2 μm emission spectra and lifetimes of Ho3+ ions in germanate glasses with different doping concentrations were investigated. The Judd-Ofelt parameters, radiative transition rates, and emission cross-section of Ho3+ were calculated based on the absorption and emission spectra. The energy transfer rate to hydroxyl groups and non-radiative rate of 5I7 level were calculated by fitting the variations of lifetimes vs. the doping concentrations. Besides, the unclad fibers with highly Ho3+ doped (6 × 1020 cm−3) were fabricated and pumped using a homemade 1.94 μm fiber laser, and the peak of emission spectra showed a redshift with the increasing fiber length.

2 μm laser properties of Tm 3+ -doped large core sol-gel silica fiber

Tm3+-doped 0.1Tm2O3-1Al2O3-98.9SiO2 (mol%) silica glass with good uniformity was prepared by sol-gel method combining with high temperature sintering. The core glass sized Φ3.2 × 50 mm with Δn of 5 × 10−4 was obtained after gelation, heat treatment, melting and polishing. Its spectroscopic properties were evaluated according to the detected absorption and fluorescence spectra. The maximum emission cross-section of Tm3+ ion in this glass is 6.2 × 10−21 cm2 and tested fluorescence lifetime is 836 μs at 1806 nm. Large core double cladding fiber with core NA of 0.102 was prepared by rod-in-tube and high temperature drawing. Its tested optical loss is 1.1 dB/m at 1333 nm. 1.11 W fiber laser output centered at 1969 nm with M2 factor of 1.99 was obtained from a 140 cm length double-cladding fiber with core diameter of 38 μm. The quasi-single mode laser with M2 factor of 1.33 was achieved in the fiber with core diameter of 19 μm.

Heavily Ho 3+ -doped lead silicate glass fiber for ~2 μm fiber lasers

A heavily Ho3+-doped lead silicate glass with low content of hydroxyls was prepared in this paper. Luminescent properties of this glass were characterized. Peak emission cross section reached 3.07 × 10−21 cm2 around 2055 nm and lifetime of Ho3+: 5I7 was fitted to be 1.31 ms. A single-cald fiber was prepared using this glass as the core. An all-fiber configuration was constructed. Under in-band core-pump of a silica fiber laser, a single-mode maximum 60 mW was realized in a 6 cm-long fiber, which shows high potential for single-frequency fiber lasers applications.

Three-level Nd3+ luminescence enhancement in all-solid silicate glass photonic bandgap fiber

We report a neodymium-doped all-solid silicate glass photonic bandgap fiber which enhances three-level laser transition ⁴F_3/2-⁴I_9/2 (890-940 nm) by suppressing the four-level laser transition ⁴F_3/2-⁴I_11/2 (1000-1100 nm) using the bandgap effect. The laser output was not obtained due to the low absorbed pump power, but our result provides a new method for a new wavelength band fiber laser.

0.5-GHz Repetition Rate Fundamentally Tm-Doped Mode-Locked Fiber Laser

We demonstrate a passively mode-locked Tm-doped silica fiber laser with 535-MHz fundamental repetition rate by employing a semiconductor saturable absorber mirror. With in-band pumping at 1590 nm, the stable mode-locked fiber laser produces up to 50 mW at an incident pump power of 558 mW. The laser operating at 1938 nm has a spectral bandwidth of 0.72 nm. After amplification, the laser pulse width is measured to be ~7.9 ps, and the time-bandwidth product is ~0.46.

All-Fiber Passively Q-Switched Laser Based on Tm 3+ -Doped Tellurite Fiber

We report all-fiber passively Q-switched Tm3±-doped tellurite fiber lasers. The composite tellurite fiber is specially designed to improve the mechanical strength. Both carbon nanotubes (CNTs) and semiconductor saturable absorber mirror (SESAM) are inserted separately into the laser cavities as SAs to demonstrate a fiber-integrated setup. In a short, 9-cm tellurite fiber, 1.86-μm-pulsed lasers without self-modelocking effect are demonstrated by in-band pumping at 1.59 μm. An average power of 84 mW is obtained in CNT-pulsed laser with 860-ns duration, whereas in SESAM-pulsed laser, the average power reaches 21 mW with 516-ns pulsewidth.

In-band pumping of Tm doped single mode tellurite composite fiber

Mechanical strength is one of the biggest limitations of practical application for tellurite fiber. In this study, we design and fabricate a single mode tellurite composite fiber to overcome the flaw. The fiber has a double cladding structure with tellurite core and inner cladding, the outer cladding, which is made of non-tellurite glass, possesses of appropriate softening temperature and coefficient of thermal expansion, well matched the novelty tellurite glass. The propagation loss of the fiber is less than 0.02 dB/cm @1310 nm. We also investigate the laser property of the fiber by using a homemade watt-class 1590 nm fiber laser. 2 micron fiber laser is demonstrated with a 2 cm length of the fiber.