München 2004 – scientific programme
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Q: Quantenoptik und Photonik
Q 42: Ultrakurze Lichtimpulse: Carrier-Envelope-Phase
Q 42.3: Talk
Thursday, March 25, 2004, 17:00–17:15, HS 223
Passive all-optical phase locking of two femtosecond Ti:sapphire lasers — •Florian Sotier1, Markus Betz1, Florian Tauser1, Stephan Trumm1, Alfred Laubereau1 und Alfred Leitenstorfer2 — 1Physik-Department E11, TU München, D-85748 Garching — 2Fachbereich Physik, Universität Konstanz, D-78457 Konstanz
Two independently tunable femtosecond Ti:sapphire lasers are passively synchronized with a stable relative carrier-envelope offset phase. Heterodyning the spectral overlap of the frequency combs from the two oscillators, we observe multiple regimes for the cavity length difference where the relative round-trip phase slip is effectively locked to zero. The phase-locking is also verified analyzing the combined optical spectrum of the two laser pulse trains. The strong correlation of the femtosecond pulse trains is maintained over minutes without any external stabilization and relative cavity lenght variations of 50 nm are compensated. Cross-phase modulation beyond the slowly varying amplitude picture is responsible for the phase synchronization. This mechanism takes full advantage of the nonresonant optical nonlinearity of the shared gain medium which is much faster than the optical cycle.