Laser processing field demand high energy pulses, thus widening pulsewidth is necessary for femtosecond pulses [1,2]. We have developed a novel method variable pulsewidth laser, which is different from conventional systems with optical BPF (Band-Pass Filter). Our pulsewidth tuning system applies a coherent coupling. When two laser-beams are coupled, output-longitudinal-modes are emitted by corresponding longitudinal modes of respective laser modules. In this study, one longitudinal-mode-space is changed arbitrary by tuning cavity length to control the output-longitudinal-modes. As the result, an envelope of the longitudinal modes, i.e. spectrum bandwidth is controlled to tune the pulsewidth.

In experiment, the laser modules of our system generate about 150 fs pulsewidth and around 30 nm spectrum bandwidth respectively. The result of the coupling, the pulsewidth is tuned with cavity length. The cavity length difference is controlled to 1.5 mm between the laser modules, and we have succeeded in widening the pulse to 1.2 ps at maximum.

1.
H.
Ito
,
N.
Goto
,
S.
Imai
(
1994
)
YAG Laser Power Transmission through an Optical Fiber and its Industrial Apphcations
,
The Review of Lase Engineering
22
.
4
:
321
328
.
2.
M.
Fujita
,
M.
Hashida
, (
2005
)
Femtosecond-Laser Processing
,
J. Plasma Fusion Res.
Vol.
81
,
195
201
3.
M.E.
Fermann
,
M.J.
Andrejco
,
M.L.
Stock
,
Y.
Silberberg
,
A.M.
Weiner
, (
1993
)
Passive mode locking erbium fiber lasers with negative group delay
,
Appl. Phys. Lett.
62
(
9
),
910
912
.
4.
Y
,
Ishida
. (
1987
)
Measurements of Ultrashort Light Pulses Using Nonlinear Correlation Methods
,
The Review of Laser Engineering
,
15-11
:
887
895
.
5.
K.
Tamura
,
C.R.
Doerr
,
L.E.
Nelson
,
H.A.
Haus
,
E.P.
Ippen
, (
1994
)
Technique for obtaining high-energy ultrashort pulses from an additive-pulse mode-locked erbium-doped fiber ring laser
,
OPTICS LETTERS
, Vol.
19
, No.
1
,
46
48
.
6.
S.
Kobtev
,
S.
Kukarin
,
S.
Smirov
,
A.I.
Latkin
,
S.
Turitsyn
, (
2009
)
High-energy all-fiber all-positive-dispersion mode-locked ring Yb laser with 8 km optical cavity length
, in
Proceedings 2009 CLEO/EQEC
,
Munich, Germany
.
7.
B.N.
Nyushkov
,
A.V.
Ivanenko
,
S.M.
kobtsev
,
S.K.
Turitsyn
,
C.
Mou
,
L.
Zhang
,
V.I.
Denisov
,
V.S.
Pivtov
, (
2012
)
Gamma-shaped Long-cavity Normal-dispersion mode-locked Er-fiber laser for sub-nanosecond high-energy pulsed generation
,
Laser Phys, Lett.
9
, No.
1
,
59
67
.
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