Dynamics of high power gain switched DFB RW laser under high current pulse excitation on a nanosecond time scale
Proc. SPIE, vol. 8640, Photonics West, San Francisco, USA, Feb. 02-07, 86401N (2013).
© 2013 COPYRIGHT SPIE--The International Society for Optical Engineering. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the SPIE.
In this paper we present detailed experimental results of the impact of the amplitude and the widths of current pulses injected into a gain-switched distributed feedback (DFB) laser emitting at a wavelength of 1064 nm. The laser with a InGaAs triple quantum well active region has a 3 µm wide ridge waveguide (RW) and a cavity length of 1.5 mm. Gainswitching is achieved by injecting current pulses with a width of 50 ns, a repetition frequency of 200 kHz and a very high amplitude up to 40 times the threshold current (2.5 A). Time resolved investigations show, that depending on the amplitude and the duration of the current pulses, the optical power exhibits different types of oscillatory behavior during the pulses, accompanied by changes in the lateral near field intensity profiles and optical spectra. Three different types of instabilities can be distinguished: Mode beating with frequencies between 25 GHz and 30 GHz, switching between different lateral modes and self-sustained oscillations with a frequency of about 4 GHz. Our results are relevant for the utilization of gain-switched DFB-RW lasers as seed lasers for fiber laser systems and in other applications, which require high optical power.
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany
Semiconductor laser, DFB-ridge waveguide laser, gain switching, mode beating.