Longitudinal data analysis of emotions of first-year students in an international degree programme

The following chapter investigate the assessment and development of students’ study paths and skills in a variety of disciplines. The final three chapters present research on student emotions and cultural perspectives, including mixed and multi-method empirical approaches. A key text for those keeping up with the current advances in the field

Universal dynamics and deterministic switching of dissipative Kerr solitons in optical microresonators

Temporal dissipative Kerr solitons in optical microresonators enable the generation of ultrashort pulses and low-noise frequency combs at microwave repetition rates. They have been demonstrated in a growing number of microresonator platforms, enabling chip-scale frequency combs, optical synthesis of low-noise microwaves and multichannel coherent communications. In all these applications, accessing and maintaining a single-soliton state is a key requirement one that remains an outstanding challenge. Here, we study the dynamics of multiple-soliton states and report the discovery of a simple mechanism that deterministically switches the soliton state by reducing the number of solitons one by one. We demonstrate this control in Si3N4 and MgF2 resonators and, moreover, we observe a secondary peak to emerge in the response of the system to a pump modulation, an effect uniquely associated with the soliton regime. Exploiting this feature, we map the multi-stability diagram of a microresonator experimentally. Our measurements show the physical mechanism of the soliton switching and provide insight into soliton dynamics in microresonators. The technique provides a method to sequentially reduce, monitor and stabilize an arbitrary state with solitons, in particular allowing for feedback stabilization of single-soliton states, which is necessary for practical applications

Scalable and Reconfigurable Optical Tap-Delay-Line for Multichannel Equalization and Correlation of 20-Gbaud QPSK signals Using Nonlinear Wave Mixing and a Microresonator Kerr Frequency Comb

We demonstrate a scalable and reconfigurable optical TDL for multichannel equalization and correlation of 20-Gbaud QPSK signals using nonlinear wave mixing and a Kerr frequency comb. The two/three-tap OTDL is demonstrated to simultaneously equalize a first signal and to search two/three-symbol patterns on another channel

Orthogonally polarized frequency comb generation from a Kerr comb via cross-phase modulation

We experimentally demonstrate that a single microresonator can emit two orthogonally polarized individually coherent combs: (i) a strong polarized soliton comb and (ii) an orthogonally polarized continuous wave seeded weaker comb, generated from the first one via cross-phase modulation, sharing the repetition rate of the soliton comb. Experimental results show that the power of the transverse electric-polarized seed can be well below the threshold of comb generation (e.g., 0.1 mW). In addition, simulations show that a dark pulse could be generated in the anomalous dispersion regime by a bright soliton when the two orthogonally polarized modes have the same group velocity in the microresonator. (C) 2019 Optical Society of Americ

Demonstration of Kramers-Kronig Detection of Four 20-Gbaud 16-QAM Channels after 50-km Transmission Using Kerr Combs to Perform Shared Phase Estimation

We experimentally demonstrate KK detection of four 20-Gbaud 16-QAM channels after 50-km transmission using two soliton Kerr combs at transmitter and receiver. The frequency comb coherence enables a shared phase noise estimation among multiple channels. (C) 2019 The Author(s