Eisuke Fujita

High power narrow-linewidth linearly-polarized 1610 nm Er:Yb all-fiber MOPA.

We developed a narrow-linewidth linearly-polarized all-PM-fiber MOPA at the wavelength of 1610 nm. The MOPA consists of a DFB laser diode seed source and three amplifier stages with three different gain fibers. The first amplifier stage employed an Er doped fiber and the second and third amplifier stages employed Er:Yb co-doped fibers. The maximum output power was 8 W. Linewidth of 25 MHz and polarization extinction ratio of 28 dB was obtained. At the maximum output power, no ASE component around 1.55 μm or 1μm was observed.

Tunable noise-like pulse generation in mode-locked Tm fiber laser with a SESAM.

We report on a tunable noise-like pulse (NLP) generation in a mode-locked Tm fiber laser with a SESAM. A tuning range of 1895-1942 nm, while keeping the spectral bandwidth of 10-19 nm under NLP mode-locked operation, was obtained by a tunable filter based on chromatic dispersion of telescope lenses. At the center wavelength of 1928 nm, the maximum output power of 195 mW with the spectral bandwidth of 18.9 nm was obtained. The repetition rate was 20.5 MHz and the corresponding pulse energy was 9.5 nJ. To our knowledge, this is the first report of a tunable NLP mode-locked laser based on chromatic dispersion of a lens system.

Kerr-lens mode-locked Tm 3+ :Sc 2 O 3 single crystal laser in-band pumped by a 1611nm Er:Yb fiber MOPA

Tm doped materials are very attractive for highly efficient high power short pulse lasers in the wavelength range of two micrometer due to their broad gain bandwidths and the two-for-one pumping process with high power 800 nm laser diodes (LD). Among them, Tm doped sesquioxides (Tm:Re<inf>2</inf>O<inf>3</inf>, Re=Sc, Lu or Y) are among the most promising gain materials as they possess superior thermal and mechanical properties and broad gain bandwidth above 1980 nm where less H2O absorption and Tm reabsorption exist. Pulses as short as 175fs, 218 fs and 148 fs were obtained previously by Ti³⁺:Al<inf>2</inf>O<inf>3</inf> laser pumped saturable absorber mode-locked Tm³⁺:Lu<inf>2</inf>O<inf>3</inf> [1], Tm³⁺:Sc<inf>2</inf>O<inf>3</inf> [2] and Tm³+:LuScO<inf>3</inf> [3] lasers, respectively. Here, we demonstrate the first Kerr-lens mode-locked (KLM) Tm³+:Sc<inf>2</inf>O<inf>3</inf> laser to our knowledge. It was in-band pumped by a 1611 nm Er:Yb fiber MOPA and generated pulses as short as 166 fs and 288fs at 440 mW and 1 W of average output power, respectively.

8 W narrow-linewidth linearly-polarized 1610 nm Er:Yb all fiber MOPA

High power linearly polarized narrow linewidth light source above the wavelength of 1600 nm are very attractive for several applications such as pump source for Cr:ZnS[1], Tm:Re2O3 (Re=Sc. Lu or Y) or nonlinear frequency conversion. Er (or Er:Yb)fibers are most popular gain media around the wavelength of 1.55 μm, though, there are few reports of Er fiber lasers above 1600 nm satisfying aforementioned properties, because the emission cross section/excited state absorption of Er ion increases/decreases as the wavelength increases[2]. They cause a difficulty of the suppression of stimulated Brillouin scattering (SBS) and amplified spontaneous emission (ASE) of Er and Yb ions. In this report, we developed a 1610 nm high power (8 W) narrow-linewidth (<25 MHz) linearly-polarized (∼28 dB) Er:Yb all-PM-fiber MOPA system.