Picosecond gain dynamics of an actively mode-locked external cavity laser diode
- Univ. Marburg (Germany). Fachbereich Physik und Zentrum fuer Materialwissenschaften
- Sandia National Labs., Albuquerque, NM (United States)
The authors present an electrical pump-optical probe experiment to investigate the temporal and spectral gain dynamics of an actively mode locked diode laser. The temporal behavior of the gain is studied with picosecond time resolution by measuring the transmission of a mode-locked Ti:sapphire laser synchronized to the semiconductor laser through the active region of the diode. Their results show that the gain transients exhibit a strong temporal asymmetry which leads to incomplete mode-locking. Investigations of the gain transients at different probe wavelengths provide the spectrum of the differential gain dg/dN. They find a pronounced increase of dg/dN towards shorter wavelengths with the dg/dN maximum blue-shifted by about 20nm from the gain maximum. From the differential gain spectrum they obtain the spectrum of the linewidth enhancement factor {alpha} via a Kramers-Kronig transformation. They find that {alpha} decreases towards shorter wavelengths and nearly vanishes in the region of maximum differential gain. Microscopic calculations based on a quasi equilibrium many-body theory yield spectra which are in good agreement with the experimental results for dg/dN and {alpha}. Based on this analysis they demonstrate a remarkable improvement of mode-locking for wavelength detuned operation and synchronous optical pumping instead of electrical modulation.
- OSTI ID:
- 64756
- Report Number(s):
- CONF-940142--; ISBN 0-8194-1441-7
- Country of Publication:
- United States
- Language:
- English
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