T. Ackemann

Realization of a semiconductor-based cavity soliton laser.

The realization of a cavity soliton laser using a vertical-cavity surface-emitting semiconductor gain structure coupled to an external cavity with a frequency-selective element is reported. All-optical control of bistable solitonic emission states representing small microlasers is demonstrated by injection of an external beam. The control scheme is phase insensitive and hence expected to be robust for all-optical processing applications. The mobility of these structures is also demonstrated.

Fundamentals and Applications of Spatial Dissipative Solitons in Photonic Devices

We review the properties of optical spatial dissipative solitons (SDS). These are stable, self‐localized optical excitations sitting on a uniform, or quasi‐uniform, background in a dissipative environment like a nonlinear optical cavity. Indeed, in optics they are often termed “cavity solitons.” We discuss their dynamics and interactions in both ideal and imperfect systems, making comparison with experiments. SDS in lasers offer important advantages for applications. We review candidate schemes and the tremendous recent progress in semiconductor‐based cavity soliton lasers. We examine SDS in periodic structures, and we show how SDS can be quantitatively related to the locking of fronts. We conclude with an assessment of potential applications of SDS in photonics, arguing that best use of their particular features is made by exploiting their mobility, for example in all‐optical delay lines.

Characteristics of polarization switching from the low to the high frequency mode in vertical-cavity surface-emitting lasers

Polarization selection in small-area vertical-cavity surface-emitting lasers is studied experimentally in dependence of injection current and substrate temperature in the vicinity of the minimum threshold condition. Polarization switching from the low to the high frequency fundamental spatial mode is demonstrated. The effective birefringence displays a minimum in the transition region. The observation of dynamical transition states hints to the relevance of nonlinear effects. A comparison to the predictions of the San Miguel–Feng–Moloney model based on phase-amplitude coupling is given.

All-optical delay line using semiconductor cavity solitons

An all-optical delay line based on the lateral drift of cavity solitons in semiconductor microresonators is proposed and experimentally demonstrated. The functionalities of the device proposed as well as its performance is analyzed and compared with recent alternative methods based on the decrease of group velocity in the vicinity of resonances. We show that the current limitations can be overcome using broader devices with tailored material responses.

Optical spin manipulation of electrically pumped vertical-cavity surface-emitting lasers

We analyze the potential for the spin manipulation of vertical-cavity surface-emitting lasers (VCSELs) by operating them electrically and injecting additional spin-polarized carriers by polarized optical excitation. The output polarization of the VCSELs can be easily controlled by the spin orientation of the optically injected carriers when the injection current does not exceed the threshold current.

Ultrafast spin-induced polarization oscillations with tunable lifetime in vertical-cavity surface-emitting lasers

We report spin-induced polarization oscillations in vertical-cavity surface-emitting lasers above threshold and at room temperature. The oscillation frequency is 11.6 GHz, which is significantly higher than the modulation bandwidth of less than 4 GHz in the device. The oscillation frequency is determined by an additional resonance frequency in birefringence containing microcavities, which is potentially much higher than the conventional relaxation oscillation frequency. The damping of the oscillations can be controlled by the current, allowing for oscillation lifetimes much longer than the spin lifetime in the device as well as for short bursts potentially interesting for information transmission.

The Gouy phase shift, the average phase lag of Fourier components of Hermite-Gaussian modes and their application to resonance conditions in optical cavities

An interpretation of the Gouy phase shift is proposed which relates the finite Gouy phase reduction of a Gaussian mode to the averaged phase retardation of the tilted waves in its Fourier spectrum compared to an on-axis plane wave. This provides a unified approach to resonance conditions in optical cavities with plane and curved mirrors. The possible relationship to pattern selection in nonlinear cavities is discussed.

Birefringence controlled room-temperature picosecond spin dynamics close to the threshold of vertical-cavity surface-emitting laser devices

We analyze the spin-induced circular polarization dynamics at the threshold of vertical-cavity surface-emitting lasers at room-temperature using a hybrid excitation combining electrically pumping without spin preference and spin-polarized optical injection. After a short pulse of spin-polarized excitation, fast oscillations of the circular polarization degree (CPD) are observed within the relaxation oscillations. A theoretical investigation of this behavior on the basis of a rate equation model shows that these fast oscillations of CPD could be suppressed by means of a reduction of the birefringence of the laser cavity.

Polarization switching to the gain disfavored mode in vertical-cavity surface-emitting lasers

We report on the experimental observation of current-induced polarization switching in vertical-cavity surface-emitting lasers which is accompanied by a decrease of the total output power at the switching point. The relaxation oscillation frequency also decreases. This switching is interpreted as a switching event from the mode with higher (unsaturated) net gain to the gain disfavored mode. The experimental observations are in qualitative agreement with a nonlinear dynamical model taking into account spin degrees of freedom of carriers in a semiconductor quantum well. Within the framework of this model, we propose an explanation for the origin of a minimum in the effective dichroism observed at the switching point, which might also be relevant for other experiments.

Characteristics of Laser Cavity Solitons in a Vertical-Cavity Surface-Emitting Laser With Feedback From a Volume Bragg Grating

In this paper, the properties of laser cavity solitons (CS) in a vertical-cavity surface-emitting laser with feedback from a volume Bragg grating (VBG) are experimentally characterized. Independent optical manipulation of all eight possible bit states of three CS is demonstrated. Tilting the VBG provides evidence for different trapping states due to device disorder. The CS are found to ldquosplitrdquo from a single peak to two peaks with increasing current, then to more complex arrangements, which are strongly governed by the spatial inhomogeneities. Due to the lack of any dominant polarizing elements, the system shows complex polarization behavior; however, each stage of the CS evolution has an approximately constant polarization angle unique for each CS. The polarization state of the CS can be controlled by adding polarization-selective or changing optics into the cavity.