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Abstract
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| The availability of suitable laser sources is one of the main challenges in future space missions for accurate measurement of atmospheric CO2. In the framework of European Project BRITESPACE, we propose an all-semiconductor laser source for an Integrated Path Differential Absorption (IPDA) lidar system for column-averaged measurements of atmospheric CO2 in future satellite missions. Standard IPDA systems use high peak power optical pulses at two sounding frequencies to calculate the column averaged gas concentration. Semiconductor lasers are superior to other types of lasers in terms of reliability, compactness and efficiency, but they cannot provide the high peak power required by the application. In consequence, the complete system architecture has to be adapted to the particular emission properties of these devices. The proposed transmitter design is based on two InGaAsP/InP monolithic Master Oscillator Power Amplifiers (MOPAs), providing the ON and OFF wavelengths close to the selected absorption line around 1.57 ?m. Each MOPA consists of a frequency stabilized Distributed Feedback (DFB) master oscillator, a modulator section, and a tapered amplifier. Initial experimental results on the fabricated MOPAs indicate that the use of a bended structure to avoid undesired feedback provides good spectral properties together with high output power and good beam quality. The modulator section is required by the Random Modulated Continuous Wave (RM-CW) approach that has been selected as the best adapted to semiconductor laser. Initial results show a good quasi-static extinction ratio when internally modulating the laser. The laser module includes the beam forming optics and the thermoelectric coolers. The DFB emission is tuned and stabilized by an offset locking technique referenced to a CO2 gas cell. A state-of-the-art InGaAs negative feedback avalanche diodes (NFAD) is proposed for single photon counting of the received signal, in order to improve the Signal to Noise Ratio. Experimental results on the MOPA and laser module characteristics will be presented. | |
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International
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Si |
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Congress
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Workshop on Laser Sources for LIDAR Applications |
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960 |
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Place
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Weßling (Germany) |
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Reviewers
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Si |
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ISBN/ISSN
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0000-0000 |
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Start Date
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25/11/2014 |
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End Date
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26/11/2014 |
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From page
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8 |
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To page
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8 |
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Workshop on Laser Sources for LIDAR Applications |