6533b827fe1ef96bd1285777

RESEARCH PRODUCT

Development of ultra-fast thulium-doped fiber lasers - Prospects for 2μm-nanophotonics.

subject

description

Developing highly coherent pulsed sources around the 2 µm wavelengthhas been a particularly dynamic field of research in the last couples of years,due to its numerous applications. In optical telecommunication, the wavelength rangearound 2 µm is one of the most promising solutions to increase the transmission capacitypast the current technological bottleneck. In this context, passively mode-lockedfiber lasers appear as a high potential solution for cheap laser sources, due to their veryhigh coherence and intrinsic compatibility with telecommunication systems.Passively mode-locked fiber lasers at 1,55 µm and their ultrafast dynamics is oneof the specialty of the ICB laboratory, and the aim is now to translate this expertisefurther in the infrared, around 2 µm by taking advantage of the optical gain of thuliumdopedfibers. This move toward the 2 µm wavelength is a current goal of the laboratory,with several research group undergoing the same transition.The first goal of the PhD. project is to transpose the techniques used in the labfrom 1,55 µ;m to 2 µm, including the various characterization experiments (spectrummeasurements, auto-correlation, fast photodiode, . . .). This work will lead to the studyof the dynamics of pulse generation around 2 µm with its similarities and differencescompared to the 1,55 µm case. Various mode-locking schemes will be studied, includingnonlinear polarization evolution, nonlinear optical loop mirrors, . . .The second part of my thesis will consist in including a micro-resonator withina fiber laser cavity and obtain a stable mode-locking. Silicon on insulator will be themain platform for this study, as its processing is well-mastered, its nonlinear effectiveindex is very high with relatively low two-photon absorption at 2 µm. On-chip high-Qmicroresonators will act as saturable absorbers leading to harmonic mode-locking withrepetition rates around 50 GHz, suitable for telecommunication applications.