| Title | CNT-based saturable absorbers with scalable modulation depth for Thulium-doped fiber lasers operating at 1.9??m. |
|---|---|
| Authors | G. Sobon; A. Duzynska; M. ?winiarski; J. Judek; J. Sotor; M. Zdrojek |
| Journal | Sci Rep |
| DOI | 10.1038/srep45491 |
| Abstract |
In this work, we demonstrate a comprehensive study on the nonlinear parameters of carbon nanotube (CNT) saturable absorbers (SA) as a function of the nanotube film thickness. We have fabricated a set of four saturable absorbers with different CNT thickness, ranging from 50 to 200?nm. The CNTs were fabricated via a vacuum filtration technique and deposited on fiber connector end facets. Each SA was characterized in terms of nonlinear transmittance (i.e. optical modulation depth) and tested in a Thulium-doped fiber laser. We show, that increasing the thickness of the CNT layer significantly increases the modulation depth (up to 17.3% with 200?nm thick layer), which strongly influences the central wavelength of the laser, but moderately affects the pulse duration. It means, that choosing the SA with defined CNT thickness might be an efficient method for wavelength-tuning of the laser, without degrading the pulse duration. In our setup, the best performance in terms of bandwidth and pulse duration (8.5?nm and 501 fs, respectively) were obtained with 100?nm thick CNT layer. This is also, to our knowledge, the first demonstration of a fully polarization-maintaining mode-locked Tm-doped laser based on CNT saturable absorber. |
See more Thulium products. Thulium (atomic symbol: Tm, atomic number: 69) is a Block F, Group 3, Period 6 element with an atomic weight of 168.93421. 
The number of electrons in each of Thulium's shells is [2, 8, 18, 31, 8, 2] and its electron configuration is [Xe]4f136s2. The thulium atom has a radius of 176 pm and a Van der Waals radius of 227 pm.
In its elemental form, thulium has a silvery-gray appearance. Thulium is representative of the other lanthanides (rare earths) and similar in chemistry to yttrium. It is the least abundant of the rare earth elements. Thulium emits blue upon excitation, and is used in flat panel screens that depend critically on bright blue emitters. Thulium was discovered and first isolated by Per Teodor Cleve in 1879. It is named after "Thule," which is the ancient name of Scandinavia.
See more Carbon products. Carbon (atomic symbol: C, atomic number: 6) is a Block P, Group 14, Period 2 element. 
The number of electrons in each of Carbon's shells is 2, 4 and its electron configuration is [He]2s2 2p2. In its elemental form, carbon can take various physical forms (known as allotropes) based on the type of bonds between carbon atoms; the most well known allotropes are diamond, graphite, amorphous carbon, glassy carbon, and nanostructured forms such as carbon nanotubes, fullerenes, and nanofibers . Carbon is at the same time one of the softest (as graphite) and hardest (as diamond) materials found in nature. It is the 15th most abundant element in the Earth's crust, and the fourth most abundant element (by mass) in the universe after hydrogen, helium, and oxygen. Carbon was discovered by the Egyptians and Sumerians circa 3750 BC. It was first recognized as an element by Antoine Lavoisier in 1789.