Detuned grating multisection-RW-DFB lasers for high-speed optical signal processing

Abstract

We present a detailed description and a first theoretical study of an improved concept for high-frequency self-pulsations (SPs) in multisection (MS)-DFB lasers with an integrated phase tuning section. The DFB wavelengths of the two DFB sections are spectrally detuned by nearly the stopband width using two gratings with different grating periods. If both DFB sections are operated at lasing conditions and an appropriate phase is chosen, we obtain beating-type SP with a frequency given by the spectral distance of two lasing modes. Good agreement between theory and experiment is obtained with respect to the role of the detuning, the role of the phase section, as well as the synchronization to external injected signals. The modeling shows a strong nonlinear coupling of the two involved modes via the carrier densities. This effect is important for the mutual coherence and for the observed locking of the beating oscillations to external signals. From the results of the calculations, we draw the conclusion that even higher SP frequencies can be obtained based on the new concept

Mutually delay-coupled semiconductor lasers: Mode bifurcation scenarios

“…This ambivalent character of delayed coupling makes this field attractive for fundamental investigations. Furthermore, delay-coupled SLs are promising candidates for different technological applications, such as secure chaos communication [4], ultra-fast optical clocks [5], and optical flip-flops [6].…”

Self-Pulsation in Multisection Distributed Feedback Laser Diode with a Novel Dual Grating Structure

“…When the injection currents of both sections are above threshold, mode beating between the modes of each section is possible. In a multisection DFB LD, the optical signal of each section is injected into the other section and this gives rise to a phase correlation between the two modes [10], [11]. The merit of mode beating is that the repetition rate is related to the mode spacing and can be varied.…”

“…In 1992, the Heinrich Hertz Institute reported the self-pulsating phenomena in multisection DFB LDs without saturable absorbers and pointed out the possibility for use in high-speed clock recovery [8], [9]. The repetition rate for their suggested structure was available up to 120 GHz [10]. They described these phenomena as dispersive Q-switching and mode beating [10]- [12].…”

“…The repetition rate for their suggested structure was available up to 120 GHz [10]. They described these phenomena as dispersive Q-switching and mode beating [10]- [12]. The origin of the self-pulsation was the mutual influence between the two gain sections in the multisection DFB LD.…”

Passively mode-locked semiconductor lasers and their applications

“…It is composed of two sub DFB sections merged to a phase section. Both sub-sections have a specific corrugation step and thus are spectrally detuned [3]. 40 GHz self-modulation of this device has been demonstrated with its potential for clock-extraction [4].…”