Abstract

Numerous applications such as free space optical communications, metrology and differential absorption lidar systems require high brightness laser sources with spectral purity. Monolithically integrated Master Oscillator Power Amplifiers (MOPAs) are promising candidates to fulfil these requirements. In particular, a three-section bent MOPA at 1.5 μm was recently proposed as laser source for an integrated path differential absorption lidar system for measurement of atmospheric CO₂ [1]. The device consists of a distributed feedback (DFB) section acting as master oscillator, a bent modulator (MOD) section and a tapered semiconductor optical amplifier (SOA) section with a tilted front facet to avoid coupled cavity effects [2]. Three separate electrical contacts on the laser chip provide access to the three sections: the DFB current controls the laser emission frequency, the MOD current allows for modulation and the SOA current drives the amplification. The MOD section acts as an absorber or amplifier when driven at zero or positive voltage bias respectively. Complete output extinction requires negative values of the MOD current due to carrier generation caused by the power injected from the DFB into the MOD section [1].

© 2017 IEEE