We propose and numerically simulate a polarization-independent 1×3 broadband beam splitter based on silicon-on-insulator (SOI) technology with adiabatic coupling. The designed structure is simulated by beam-propagation-method (BPM) and gets simulated transmission uniformity of three outputs better than 0.3dB for TE-polarization and 0.8dB for TM-polarization in a broadband of 180nm.
Proc. SPIE. 9267, Semiconductor Lasers and Applications VI
KEYWORDS: Semiconductors, High power lasers, Laser applications, Photonic crystals, Semiconductor lasers, Optoelectronics, Near field, Vertical cavity surface emitting lasers, Laser crystals, Chemical elements
We design photonic crystal (PC) array surface emitting lasers with large-area coherence. The structure has six-fold rotational symmetry. By finite-difference time-domain method, we investigate the far-field characteristics of the individual element and the array. We demonstrate theoretically that the coherent PC array has lower far-field divergence angles and higher power compared to those of individual elements. Our PC array exhibits strong leaky coupling which has high mode stability and high intermodal discrimination. Thus, the coherent PC array shows great potential for high power low divergence in-phase surface laser emitting.
Edge-emitting laser diodes operating at 900 nm are designed and fabricated with an epitaxial one-dimensional
photonic crystal (PC). PC structure consists of a p-waveguide layer, an active quantum region, and an
n-waveguide layer. The p-cladding totally reflects one tilted optical mode. The PC with a particular band
structure confines the optical mode with a certain tilted angle. Meanwhile mode extends vertically due to the
photonic band modulation at the direction perpendicular to the interface. Then we obtain the broad-area lasers
with a narrow vertical far-field divergence of 10°, and a small thermal shift (dλ/dT~-0.06 nm/K) in continuous
The Bragg diffraction condition of surface-emitting lasing action is analyzed and Γ2-1 mode is chosen for lasing. Two
types of lateral cavity photonic crystal surface emitting lasers (LC-PCSELs) based on the PhC band edge mode lateral
resonance and vertical emission to achieve electrically driven surface emitting laser without distributed Bragg reflectors
in the long wavelength optical communication band are designed and fabricated. Deep etching techniques, which rely on
the active layer being or not etched through, are adopted to realize the LC-PCSELs on the commercial AlGaInAs/InP
multi-quantum-well (MQW) epitaxial wafer. 1553.8 nm with ultralow threshold of 667 A/cm<sup>2</sup> and 1575 nm with large
power of 1.8 mW surface emitting lasing actions are observed at room temperature, providing potential values for mass
production with low cost of electrically driven PCSELs.
Under high concentration the temperature of photovoltaic solar cells is very high. It is well known that the efficiency and
performance of photovoltaic solar cells decrease with the increase of temperature. So cooling is indispensable for a
concentrator photovoltaic solar cell at high concentration. Usually passive cooling is widely considered in a concentrator
system. However, the thermal conduction principle of concentrator solar cells under passive cooling is seldom reported.
In this paper, GaInP/GaAs/Ge triple junction solar cells were fabricated using metal organic chemical vapor deposition
technique. The thermal conductivity performance of monolithic concentrator GaInP/GaAs/Ge cascade solar cells under
400X concentration with a heat sink were studied by testing the surface and backside temperatures of solar cells. The
tested result shows that temperature difference between both sides of the solar cells is about 1K. A theoretical model of
the thermal conductivity and thermal resistance of the GaInP/GaAs/Ge triple junction solar cells was built, and the
calculation temperature difference between both sides of the solar cells is about 0.724K which is consistent with the
result of practical test. Combining the theoretical model and the practical testing with the upper surface temperature of
tested 310K, the temperature distribution of the solar cells was researched.
GaSb based cells as receivers in thermophotovoltaic system have attracted great interest and been extensively studied in
the recent 15 years. Although nowadays the manufacturing technologies have made a great progress, there are still some
details need to make a further study. In this paper, undoped and doped GaSb layers were grown on n-GaSb (100)
substrates from both Ga-rich and Sb-rich solutions using liquid phase epitaxy (LPE) technique. The nominal segregation
coefficients <i>k</i> of intentional doped Zn were 1.4 and 8.8 determined from the two kinds of GaSb epitaxial layers.
Additionally, compared with growing from Ga-rich solutions, the growing processes from Sb-rich solutions were much
easier to control and the surface morphologies of epitaxial layers were smoother. Furthermore, in order to broaden the
absorbing edge, Ga<sub>1-x</sub>In<sub>x</sub>As<sub>y</sub>Sb<sub>1-y</sub> quaternary alloys were grown on both GaSb and InAs substrates from In-rich solutions,
under different temperature respectively.