Study on High-Power Spectral-Flat 2-2.5 μm Supercontinuum Laser Source

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Important Dates

Conference:

Aug. 18-20, 2018

Full Paper Due: Jul. 20, 2018

Abstract Due: Jul. 20, 2018

Audience Registration Due:
Aug. 18, 2018

Presentations of The Int'l Symposium on Photonics and Optoelectronics (SOPO 2016)

● Study on High-Power Spectral-Flat 2-2.5 μm Supercontinuum Laser Source
Author(s)
Ke Yin
Affiliation(s)
National university of defense technology
KEYWORDS
High-Power Spectral-Flat 2-2.5 μm, Supercontinuum, Laser Source
ABSTRACT
2-2.5 μm supercontinuum (SC) laser sources locate at the infrared atmospheric window, indicat-ing that there are lots of important atmospheric applications of these broadband sources. In this paper, a spectral-flat 2-2.5 μm SC source with optimized maximum output power of >200 W is re-ported by adopting a cladding pumped thulium-doped fiber amplifier. The underlying physical mechanisms behind the SC generation process are investigated firstly with a numerical model which includes the fiber gain and loss, the dispersive and nonlinear effects. Simulation results show that abundant soliton pulses are generated in the TDFA, and they are shifted towards the long wavelength side very quickly with the nonlinearity of Raman soliton self-frequency shift (SSFS), and eventually the Raman SSFS process is halted due to the silica fiber’s infrared loss. A spectrally-flat 2-2.5 μm SC source could be generated as the result of the spectral superposition of these abundant soliton pulses. These simulation results correspond qualitatively well to the following experimental results. The evolutions of the output spectrum and power of the SC source and temperature of the fiber endcap are investigated in details. When the repetition rate of the seed pulses is 2 MHz and 4 MHz, the obtained maximum output power of the 2-2.5 μm SC laser source is 157 W and 203.4 W, which corresponds to a 3 dB spectral bandwidth of 550 and 545 nm, respectively. At the highest output power, the power spectral intensity is calculated to be as high as 370 mW/nm, which is the bright-est 2-2.5 μm SC laser source ever reported. The results indicate that by increasing the repetition rate of the seed pulses, the SC conversion efficiency of the fiber amplifier could be scaled together with a less infrared absorption loss of the long wavelength spectral components. Meanwhile, the output SC source has a good beam profile. This SC laser source, to the best of our knowledge, is the brightest spectrally-flat 2-2.5 μm light source ever reported. It will be highly desirable in a lot of long-range atmospheric applications, such as broad-spectrum LIDAR, free space communication and hyper-spectral imaging.