Spectral narrowing in gases using femtosecond laser pulses
| Autor: | Aditya K. Dharmadhikari, J. A. Dharmadhikari, Tanvi Karpate, Deepak Mathur |
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| Rok vydání: | 2017 |
| Předmět: |
Femtosecond pulse shaping
Amplified spontaneous emission Materials science Active laser medium business.industry Physics::Optics Pulse duration 02 engineering and technology 021001 nanoscience & nanotechnology Laser 01 natural sciences law.invention Optics law 0103 physical sciences Femtosecond 010306 general physics 0210 nano-technology business Ultrashort pulse Lasing threshold |
| Zdroj: | SPIE Proceedings. |
| ISSN: | 0277-786X |
| Popis: | Filamentation in gases due to high power femtosecond pulses results from the combined action of the optical Kerr effect (giving rise to self-focusing) and plasma formation (giving rise to defocusing) that confines optical energy in a small region over a distance longer than the Rayleigh range. Since the discovery of N2 as a potential gain medium, which subsequently led to the formation of nitrogen lasers, it has held a keen interest due to its potential in achieving lasing by remote excitation. Recently, Yamanouchi and coworkers demonstrated lasing action in N2 in the forward as well the backward directions along the femtosecond pulse propagation. In the present work, we have focused on excitation of N2 + (corresponding to the 391nm spectral feature) and have measured spectral narrowing. We have investigated the influence exerted by the incident pulse power and gas pressure for incident pulses of durations 40 fs and 10 fs in forward and backward detection modes. Spectral narrowing that occurs for N2 gas at 391 nm shows a dependence on the incident pulse duration. Pressure threshold for different incident powers for lasing has been established. Increase in the signal intensity on varying the incident power is ascribed to amplified spontaneous emission (ASE). White-light-seeded lasing in N2 + is generated by a Ti:sapphire femtosecond laser for different focusing. The lasing lines peak over the trail of the incident broadband spectra. |
| Databáze: | OpenAIRE |
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