There have been much interests in the semiconductor microcavity lasers based on quasi-two-dimensional cavity geometry. Tailoring the cavity boundary shape can induce chaotic ray dynamics, and has a profound impact on the properties of cavity resonances. In the first part of this talk, we will show a wave-chaotic cavity allows many modes lase simultaneously, and the spatial coherence of emission is reduced. The leads to the application of chaotic microcavity lasers as illumination source for speckle-free full-field imaging. In the second part of this talk, we show that lasing instabilities are suppressed in wave-chaotic cavities, due to disruption of filamentation.

It is well known that piezoelectric polarization in III-nitride heterostructures causes a significant spatial separation of electrons and holes inside quantum wells (QWs). It is detrimental to optoelectronic devices due to the decreased oscillator strength. In this work we will show that wide InGaN QWs, despite extremely low wavefunction overlap between the ground electron and hole states, can have higher efficiency than the regularly used thin QWs. We propose a model in which the high efficiency comes from transitions through the excited states. Finally, application of the wide QWs to optoelectronic devices will be presented.

Stimulated Brillouin Scattering (SBS) provides a major limitation on power scaling in high power fiber lasers and amplifiers. Using wavefront shaping in highly multimode fibers provides a promising avenue to suppress SBS while maintaining good beam quality. We present here a generalized theory for SBS in multimode fiber amplifiers. We find the Stokes susceptibility in terms of eigenmode expansions of the vector optical and acoustic wave equations. An analytical form of the relevant gain matrix is obtained in terms of modal overlap integrals. We will discuss wavefront shaping strategies to suppress SBS based on the properties of the gain matrix.

We employ a quantum mechanical model to describe nonclassical effects in the optical response of crystalline noble metal films, demonstrating that such effects can be contained in quantum surface-response functions known as Feibelman d-parameters. In particular, we extract d-parameters characterizing the surface response of (111) and (100) crystallographic facets of silver, gold, and copper, and apply them in simple optical response calculations to capture important features emerging due to electron spill-in/out, surface states, and the projected electronic gap emerging from corrugation of the confinement potential by stacked atomic planes.

In this contribution, we analyze the photogating effect in InP nanowire arrays with embedded InAsP quantum discs by detailed numerical modeling. The model comprises a drift-diffusion current coupled to the nonlinear Poisson equation, solved on a 2-dimensional geometry with rotational symmetry. By comparison to experimental data, surface trap states are identified that explain both the current versus voltage behavior in dark and under illumination. The current versus illumination power is highly nonlinear, and shows measured gain up to 320 for a power of 20 nW at 980 nm for an array of millions of wires.

The ultraviolet-A (UVA) emitting and the solar-blind photo-detecting device was successfully demonstrated by the ZnGa2O4 oxide layer in a metal-oxide-semiconductor (MOS) structure. The ZnGa2O4 oxide layer was deposited on Si substrate through a facile sol-gel precursor method with optimization of annealing temperatures as a light-emitting and photo-detecting layer. The ITO was deposited by a sputter with a 100 μm stripe pattern for the transparent electrode. It emits the broad UVA light which is attributed to the self-activating ZnGa2O4 and shows an exponential increase and a gradual increase according to the applied voltages and frequencies, respectively. Moreover, it provides a decent response in a photo-detection, especially as a solar-blind photodetector. Finally, we present the UVA photocatalytic effect with an additional TiO2 layer and the photo-detecting response with dark current (Idark) and photocurrent (Iphoto¬) ratio in various conditions.

We investigate the possibility of probing the electrical status of a p-i-n junction via an optical fiber, without the need for electrical contacts. A photonic crystal with a resonance in the near-infrared is etched in a thin membrane of III-V semiconductor with an embedded p-i-n junction and placed on the cleaved facet of a fiber. We measure the effect of photoexcited carriers on the built-in voltage of the diode through the Pockels effect. This may enable the all-optical read-out of electrical signals from sensors in a distant or inaccessible environment.

Nanowire lasers can be monolithically and site-selectively integrated onto silicon photonic circuits. To assess their full potential for ultrafast opto-electronic devices, a detailed understanding of their lasing dynamics is crucial. However, the roles played by their resonator geometry and the microscopic processes that mediate energy exchange between the photonic, electronic, and phononic systems are largely unexplored. Here, we apply femtosecond pump-probe spectroscopy to show that GaAs-AlGaAs core-shell nanowire lasers exhibit unexpected non-equilibrium dynamics occurring over few picosecond timescales. As we will show, these dynamics are intricately linked to the strong interaction between the lasing mode and the gain material arising from their wavelength-scale dimensions. We anticipate that our results will lead to new approaches for ultrafast intensity and phase modulation of chip-integrated nanoscale semiconductor lasers.

We show via a combination of material realistic quantum-kinetic theory and experimental differential pump-probe results, that performance issues in tunnel-injection QD lasers are caused by a filtering effect, resulting from the hybridization of different QD shells with the injector quantum well. The real footprint of applicability in optical communication system is the large signal modulation response, which, on the other hand is much less often investigated.

We investigate the evolution of current spreading, injection, and radiative differential efficiencies in InAs/InP quantum dash and InGaAsP quantum well lasers operating at 1550 nm under varying temperatures up to 80°C. Simulations in Crosslight PICS3D are compared to fabricated devices. The injection efficiency remains largely unaffected by temperature, with less efficient radiative recombination and current spreading accounting for the temperature sensitivity of device performance. A temperature-dependent 10% to 14% difference in the current spreading efficiency emerges as the primary cause of lower simulated efficiencies in these quantum dash lasers compared to the quantum wells.