There are natural limits to the spatial resolution and the deposited energy densities that can be achieved in femtosecond laser dielectric modification. These arise because of the threshold-like nature of nonlinear absorption. We use two-pulse experiments to show that both limits can be exceeded by taking advantage of absorption seeded by free electrons or self-trapped excitons, depending on the pulse separation.

1.
K. M.
Davis
,
K.
Miura
,
N.
Sugimoto
, and
K.
Hirao
, “
Writing waveguides in glass with a femtosecond laser
,”
Opt. Lett.
21
,
1729
(
1996
).
2.
R. R.
Gattass
and
E.
Mazur
, “
Femtosecond laser micromachining in transparent materials
,”
Nature Photon.
2
,
219
225
(
2008
).
3.
K.
Miura
,
J. R.
Qiu
,
H.
Inouye
,
T.
Mitsuyu
, and
K.
Hirao
, “
Photowritten optical waveguides in various glasses with ultrashort pulse laser
,”
Appl. Phys. Lett.
71
,
3329
(
1997
).
4.
D. M.
Rayner
,
A.
Naumov
, and
P. B.
Corkum
, “
Ultrashort pulse non-linear optical absorption in transparent media
,”
Opt. Express
13
,
3208
(
2005
).
5.
V. R.
Bhardwaj
,
P. P.
Rajeev
,
P. B.
Corkum
, and
D. M.
Rayner
, “
Strong field ionization inside transparent solids
,”
J. Phys. B
39
,
S397
(
2006
).
6.
E.
Yablonovitch
and
N.
Bloembergen
, “
Avalanche ionization and the limiting diameter of filaments induced by light pulses in transparent media
,”
Phys. Rev. Lett.
29
,
907
910
(
1972
).
7.
B. C.
Stuart
,
M. D.
Feit
,
S.
Herman
,
A. M.
Rubenchik
,
B. W.
Shore
, and
M. D.
Perry
, “
Nanosecond-to-femtosecond laser-induced breakdown in dielectrics
,”
Phys. Rev. B
53
,
1749
1761
(
1996
).
8.
D.
Grojo
,
M.
Gertsvolf
,
S.
Lei
,
T.
Barillot
,
D. M.
Rayner
, and
P. B.
Corkum
, “
Exciton-seeded multiphoton ionization in bulk SiO2
,”
Phys. Rev. B
81
,
212301
(
2010
).
9.
C
Itoh
,
K
Tanimura
, and
N
Itoh
, “
Optical studies of self-trapped excitons in SiO2
,”
J. Phys. C
21
,
4693
(
1988
).
10.
C. B.
Schaffer
,
J. F.
Garcia
and
E.
Mazur
, “
Bulk heating of transparent materials using a high repetition-rate femtosecond laser
,”
Appl. Phys. A
76
,
351
354
(
2003
).
11.
C. N.
Berglund
and
R. J.
Powell
, “
Photoinjection into SiO2: Electron scattering in the image force potential well
,”
J. Appl. Phys.
42
,
573
(
1971
).
12.
X.
Yu
,
Q.
Bian
,
B.
Zhao
,
Z.
Chang
,
P. B.
Corkum
, and
S.
Lei
, “
Near-infrared femtosecond laser machining initiated by ultraviolet multiphoton ionization
,”
Appl. Phys. Lett.
102
,
101111
(
2013
).
You do not currently have access to this content.