Relative Intensity Noise in Er:ZBLALiP Whispering Gallery Mode Laser : Theory and Experiments
Patrice Féron(1)*, Jean-Baptiste Ceppe(1,2), Michel Mortier(3), Yannick Dumeige(1).
(1) CNRS, UMR 6082 Foton, Enssat, 6 rue de Kerampont, CS 80518, 22305 Lannion, France.
(2) IRCICA (CNRS USR 3380) - PhLAM (CNRS UMR 8523), 50 Avenue du Hallay, 59650 Villeneuve d'Ascq, France
(3) IRCP (CNRS-UMR 8247), Chimie-Paristech, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05, France.
*corresponding author firstname.lastname@example.org +33296469042
Fiber Lasers and Glass Photonics: Materials through Applications
Fibers and Waveguide Sources – metrology and testing methods for laser sources
Micro spherical resonators have attracted significant attention in recent years due to their interesting optical properties and the range of applications for which they can be used. Most of the publications dedicated to micro spherical Laser are devoted to lasing effects in different materials where the spectral properties of the emission depends on (i) the choice of dopant (e.g. Er3+, Yb3+, Tm 3+) and (ii) the host matrix (e.g. silica, fluoride, phosphate or telluride glass) in which the dopant is embedded. Yet, the dynamics of theses Lasers are still to be studied. This paper shows experimental and theoretical results on the amplitude fluctuations of a Whispering Gallery Mode Laser, also known as relative intensity noise (RIN). It gives information about the dynamics inside the cavity, such as photon lifetime, effective pumping rate and noise sources. We use as active medium Er3+ doped fluoride ZBLALiP glass. Theses glasses are well adapted to the development of micro spherical Laser operating in the infrared region, in particular with emission wavelengths falling respectively in the C-band.
In this paper we report on the RIN measurements for several pumping configurations of Erbium doped fluoride glass WGM micro-lasers. Due to the unique properties of WGM resonators, harmonics of the spiking frequency are observed in the RIN spectrum. Usual model of class B laser has been extended to take into account WGM specificities in order to exploit the experimental results. The model including nonlinear coupling of population inversion and photon number fluctuations is well suited for the description of low mode volume WGM lasers for which this coupling is not negligible. The comparison between experiments and our model allow relevant physical parameters to be extracted from the fitting of the RIN spectrum (as example mode volume and quantum numbers of the WGM). Our approach could be extended to WGM laser frequency noise and exploited in the analysis of the whole noise properties of micro-lasers used in sensor applications.