Stewart, George and Arsad, Norhana (2009) Intra-cavity spectroscopy using amplified spontaneous emission in erbium fibre lasers. Proceedings of SPIE: The International Society for Optical Engineering, 7503. 750312-1 - 750312-4.Full text not available in this repository. (Request a copy from the Strathclyde author)
Fibre laser sources offer interesting possibilities for gas sensors since they can operate over an extended wavelength range, encompassing the near-IR absorption lines of a number of important gases but a major problem is that overtone absorption lines of gases in the near-IR are relatively weak. In order to enhance sensitivity, we present here a simple method of intra-cavity laser absorption spectroscopy (ICLAS) which makes use of the amplified spontaneous emission (ASE) already present within a fibre laser cavity. The ASE also provides a convenient broad-band source for the interrogation of several gases within the gain-bandwidth of the fibre laser. The key principle is based on adjusting the cavity attenuation to select an appropriate inversion level and hence flatten the erbium-fibre gain curve. Under this condition, the ASE undergoes multiple circulations within the fibre laser cavity, enhancing the effective path-length of a gas cell placed within the laser cavity. We have experimentally demonstrated the principle of operation with acetylene gas, using a simple erbium fibre laser system containing a 6cm path-length, fibre coupled, intra-cavity, micro-optic gas cell. For 1% acetylene gas, we have experimentally observed 16 absorption lines in the 1530nm region and a path length enhancement of ~60 has been demonstrated, transforming the 6cm micro-optic cell into an effective path length of ~3.5m. Apart from the OSA, all components are inexpensive and the system is very simple to construct and operate.
|Keywords:||intra-cavity spectroscopy, laser spectroscopy, erbium-doped fibre lasers, fibre sensors, gas sensors, Electrical engineering. Electronics Nuclear engineering, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Electrical and Electronic Engineering, Applied Mathematics, Computer Science Applications|
|Subjects:||Technology > Electrical engineering. Electronics Nuclear engineering|
|Department:||Faculty of Engineering > Electronic and Electrical Engineering|
|Depositing user:||Pure Administrator|
|Date Deposited:||28 Jun 2011 13:37|
|Last modified:||27 Apr 2016 16:58|