See Fig. 4 (a) and (b) in

Sho Itoh, Hirofumi Hidai, Hitoshi Tokura,
Experimental and numerical study of mechanism of glass modification process by continuous-wave laser backside irradiation (CW-LBI),
Applied Physics A
September 2013, Volume 112, Issue 4, pp 1043-1049
http://dx.doi.org/10.1007/s00339-012-7477-2

An interesting report written in Russian:

D. A. Dvoreckii, V. F. Hopin, A. N. Gur’yanov, L. K. Denisov, L. D. Ishakova and I. A. Bufetov:
“Optical losses in silica based fibers within the temperature range from 300 to 1500 K”,
Science and Education: electronic scientific-technical journal, 5 (2013).

My paper in Japanese is published. This topic will be given in my OFC/NFOEC poster on 20th March (JW2A.11). You can download it for free from here (click “PDF” in the page) and see figures with English captions.

S. Todoroki: “Modes and threshold power of fiber fuse propagation”, IEICE Trans. Commun. B, J96-B, 3, pp. 243-248 (2013).
(in Japanese, open access).

Three modes of fiber fuse propagation are defined for SMF and NZ-DSF on the basis of pump power dependence of its propagation speed and damage structure. In cylindrical mode and unimodal mode, enclosed plasma occupies fully in the radial direction and leaves a void train with and without periodicity, respectively. In unstable mode, the cross-sectional area of the plasma is smaller than that in other two modes and vulnerable to the irregularity of the waveguide structure. Threshold power for fuse propagation should be carefully determined without accidental termination due to this vulnerability.