Direct observations of thermalization to a Rayleigh–Jeans distribution in multimode optical fibres

Interplay of thermalization and strong disorder: Wave turbulence theory, numerical simulations, and experiments in multimode optical fibers

“…By adjusting the applied stress, we can tune the strength of mode coupling (i.e., σ). In the absence of an applied stress, polarization coupling and random coupling among degenerate modes take place: In this weak random coupling regime the energy E = j β j w j is conserved during light propagation in the MMF [23,25], as confirmed by direct experimental measurements [24,[29][30][31][32]. Here, we apply stress on the MMF to induce a random coupling among non-degenerate modes [45][46][47][48]53].…”

“…This phenomenon received a recent renewed interest with the discovery of spatial beam cleaning in multimode optical fibers (MMFs) [19][20][21]. Along this line, RJ thermalization and light condensation in MMFs have been discussed [22][23][24][25][26][27][28] and recently observed experimentally [29][30][31][32][33].…”

“…[29] for details. Here, the originality with respect to all previous experiments on beam cleaning condensation and thermalization [19][20][21][29][30][31][32], is that we introduce strong disorder in the experiment. Strong mode coupling is obtained by applying a stress to the MMF with clamps [49].…”

Experimental observation of spontaneous emission of space-time wavepacket in a multimode optical fiber

“…This simply lies in the possible fine control and analysis of transversal modes that can propagate and interact, in contrast to limiting cases of single-mode waveguides and bulk media with their infinite and continuous set of modes. Over the past few years very exciting observations have been reported in terms of novel optical effects, such as geometric parametric instability, beam self-cleaning, light thermalization processes, multimode solitons, and spatiotemporal laser mode-locking, to name a few [1][2][3][4][5][6][7][8]. When combining the potential of multimode waveguides with recent technological advances in laser sources and pulse shaping, one of the most promising development relates to the generation and application of propagation-invariant spatiotemporal (ST) wavepackets [9][10][11][12][13].…”

Spectral Shaping in a Multimode Fiber by All-fiber Modulation

“…In the past decade there is ongoing effort to utilize multimode optical fibers (MMF) in a wide range of photonic applications such as optical fiber communication [1][2][3], high energy fiber lasers [4][5][6], quantum optics [7][8][9][10][11], nonlinear optics [12][13][14][15][16][17][18] and imaging [19][20][21][22][23][24][25][26]. The challenge of MMF-based technologies is that transverse modes of the fiber are interrupted by inter-modal interference, mode coupling, and modal dispersion.…”