Multi-gas dual-comb spectroscopy with tunable gain-switched laser diodes.

This study presents a tunable multi-gas spectroscopic scheme using a dual-comb architecture operating within the near-infrared domain. The dual-comb signal is generated by two gain-switched Fabry-Perot laser diodes at low repetition rates and externally injected by a tunable laser source. A systematic study on the injection wavelength, line spacing and optical span performed over the system, ensures the generation of stable optical frequency combs with a 40 GHz bandwidth, and more than 400 lines at a low repetition rate (100 MHz).

Generation of optical frequency combs by Q-switching integrated multi-section semiconductor lasers.

In this work we perform a theoretical and simulation analysis of the behavior of an integrated four section distributed Bragg reflector semiconductor laser under optical injection and Q-switching operation. An electro-absorption modulator is introduced into the laser cavity to control the total losses and perform Q-switching. The simulations are done using a rate equation model.

Gain-switched semiconductor lasers with pulsed excitation and optical injection for dual-comb spectroscopy.

In this work we demonstrate the capability of two gain-switched optically injected semiconductor lasers to perform high-resolution dual-comb spectroscopy. The use of low duty cycle pulse trains to gain switch the lasers, combined with optical injection, allows us to obtain flat-topped optical frequency combs with 350 optical lines (within 10 dB) spaced by 100 MHz. These frequency combs significantly improve the spectral resolution reported so far on dual-comb spectroscopy with gain-switched laser diodes.

Enhanced optical frequency comb generation by pulsed gain-switching of optically injected semiconductor lasers.

We report on the experimental generation of broad and flat optical frequency combs (OFC) in a 1550 nm laser diode using gain switching with pulsed electrical excitation together with optical injection. The combination of both techniques allows the generation of high-quality OFCs at a repetition frequency of 500 MHz, showing a low-noise optical spectrum with unprecedent features in terms of width (108 tones within 10 dB) and flatness (56 tones within 3 dB) in comparison with those previously reported for this modulation frequency. The influence of the injection conditions on the OFC quality is studied.

Analysis of a random modulation single photon counting differential absorption lidar system for space-borne atmospheric CO sensing.

The ability to observe the Earth's carbon cycles from space provides scientists an important tool to analyze climate change. Current proposed systems are mainly based on pulsed integrated path differential absorption lidar, in which two high energy pulses at different wavelengths interrogate the atmosphere sequentially for its transmission properties and are back-scattered by the ground. In this work an alternative approach based on random modulation single photon counting is proposed and analyzed; this system can take advantage of a less power demanding semiconductor laser in intensity modulated continuous wave operation, benefiting from a better efficiency, reliability and radiation hardness.