Defense of the doctoral thesis of Thomas MONCOND’HUY, for the University Grenoble Alpes , speciality "OPTICS & RADIOFREQUENCIES ", entitled:
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Development of mineral saturable absorbers for the realization of glass integrated Q-switched lasers
Thursday, April 4th, 2019 at 10:00
Since its creation in 1960, laser has become a really useful tool. Lasers are very versatile and they has become part of many of our everyday life tools. Coming in their pulsed form, lasers have opened-up others fields of application such as machining, cutting, marking or cleaning materials; or medicine and well-being and also sensors and in particular embedded sensors. Passively Q-Switched lasers are particularly adapted to this last field of application thanks to their energetic self-sufficiency, using the energy of the laser itself to create very energetic laser pulses whose duration order is about the nanosecond. The lasers made on optical glass wafers have also proved very suitable for the manufacture of on-board sensing devices: they show great stability, strong mechanical and chemical resistance, making them usable in a wide range of environmental conditions.
At IMEP-LaHC, lasers made by silver / sodium ion exchange in erbium and ytterbium doped phosphate glasses were made. Pulsed lasers have also been realized using this planar waveguide technology in interaction with thin films of cellulose acetate doped with a dye named BDN, having the saturable absorption properties needed for the emergence of Q –Switch operation. These lasers can already address on-board sensing applications. However, some applications require even more power and above all a better environmental resistance than that proposed by cellulose acetate. In order to meet all these expectations, we present in this manuscript the production of saturable absorbers from BDN-doped sol-gel matrices to create saturable absorber waveguides. Specific characterization methods and saturable absorption simulations are developed to describe the operation of such devices and to evaluate the relevance of the choice of such matrices allied with BDN dye in order to create glass integrated Q-Switched lasers.