High-power, sub-100-fs, 1600-1700-nm all-fiber laser for deep multiphoton microscopy.

The 1600-1700-nm ultrafast fiber lasers attract great interests in the deep multiphoton microscopy, due to the reduced levels of the tissue scattering and absorption. Here, we report on the 86.7-MHz, 717-mW, 91.2-fs, all-fiber laser located in the spectral range from 1600 nm to 1700nm. The soliton self-frequency shift (SSFS) was introduced into the Er:Yb co-doped fiber amplifier (EYDFA) to generate the high-power, 1600-1700-nm Raman soliton. Detailed investigations of the nonlinear fiber amplification process were implemented in optimizing the generated Raman soliton pulses. The miniature multiphoton microscopy was further realized with this home-built laser source. The clearly imaging results can be achieved by collecting the generated harmonic signals from the mouse tail skin tissue with a penetration depth of ∼500 µm. The experimental results indicate the great potential in utilizing this 1600-1700-nm fiber laser in the deep multiphoton microscopy.

Two-photon endomicroscopy with microsphere-spliced double-cladding antiresonant fiber for resolution enhancement.

We demonstrate a miniature fiber-optic two two-photon endomicroscopy with microsphere-spliced double-cladding antiresonant fiber for resolution enhancement. An easy-to-operate process for fixing microsphere permanently in an antiresonant fiber core, by arc discharge, is proposed. The flexible fiber-optic probe is integrated with a parameter of 5.8 mm × 49.1 mm (outer diameter × rigid length); the field of view is 210 µm, the resolution is 1.3 µm, and the frame rate is 0.7 fps. The imaging ability is verified using ex-vivo mouse kidney, heart, stomach, tail tendon, and in-vivo brain neural imaging.

Femtosecond all-polarization-maintaining Nd fiber laser at 920†nm mode locked by a biased NALM.

We demonstrate a femtosecond all-polarization-maintaining Nd fiber laser working at 920 nm mode locked by a biased non-linear loop mirror. The broadest spectral width of the pulse is 25.2 nm and the output power is 8 mW with 320 mW pump power. The measured pulse width is 109 fs with extra-cavity compression. The laser configuration of all-polarization-maintaining fiber can directly enhance the environmental stability of generated pulses. The seed pulses of the oscillator were amplified over 400 mW, which served as the light source for a two-photon microscope. To the best of our knowledge, this is the first demonstration of a 920 nm femtosecond Nd polarization-maintaining fiber laser based on a non-linear loop mirror.