Multispectral imaging microscopy is a novel microscopic technique that integrates spectroscopy with optical imaging to record both spectral and spatial information of a specimen. This enables acquisition of a large and more informative dataset than is achievable in conventional optical microscopy. However, such data are characterized by high signal correlation and are difficult to interpret using univariate data analysis techniques.
Kaduki, KA.
2013. The Status of Physics in Kenya. 3rd International Conference on High Level Physics and Appropriate Solutions to Real Life Problems in Developing Countries. , 25 Abstract
Omucheni, DL, Kaduki KA, Angeyo HK, Bulimo WD, Zoueu JT.
2012. A joint Kenya – Ivory Coast Malaria Measurement Campaign, 14-29 September. African Spectral Imaging Network (AFSIN) International Workshop on Spectral Imaging in Remote Sensing. , Nairobi, Kenya
By device simulation, it is shown that non-square quantum well growth (well shaping) provides a means for reducing the threshold current of bipolar quantum well diode lasers. Calculations of subband structure, optical matrix elements and laser gain are performed based on a 4-band (electron, heavy-hole, light-hole, split-off-hole) Hamiltonian with Burt-Foreman Hermitianization. A non-optimized, compressively strained, InGaAs-AlGaAs (on GaAs) shaped well laser, operating at 0.97 µm is predicted to show improvements in both radiative and non-radiative current performance compared to a device based on an optimal square quantum well of the same well width and emission wavelength. These improvements result from modification of subband structure giving greater subband separation in the shaped well than in the square well
We describe Envelope Function Approximation (EFA) bandstructure calculations based on a 4-band electron (EL), heavy-hole (HH), light-hole (LH) and split-off hole (SO) effective mass Hamiltonian, with Burt-Foreman hermitianisation, which can handle III-V quantum well structures that incorporate ultra-narrow epi-layers. The model takes into account the coupling of EL, HH, LH and SO bands and is suitable for describing quantum wells tuned to the 1.0 - 1.55 µm window exploited by optical fibre communication devices. We have used the multi-band solver to calculate the bandstructure of an illustrative InGaAsSb-AlGaSb non-square quantum well that incorporates 6Å potential "spikes" in its well region. Calculations based on the Burt-Foreman hermitianised Hamiltonian and those based on a Hamiltonian with standard "symmetrised" hermitianisation are presented and compared. When coupling to the conduction band is excluded from the calculation, the latter formulation leads to anomalous electron-like curvature of the dispersion curves for our spiked non-square quantum well structure
This paper presents calculations demonstrating that non-square quantum well growth
(well shaping) can result in reduced threshold current for tensilely strained quantum well bipolar
diode lasers operating at 1.52μm m. Calculations of subband structure, optical matrix elements and
laser gain are performed for arbitrarily shaped quantum wells based on a 4-band (electron/heavyhole/
light-hole/split off-hole) Hamiltonian. For long wavelength (1.3μm m to 1.55μm) lasers,
Auger recombination dominates the threshold current. Compared to a 1.52 mm optimal square well
just below critical thickness, an InGaAs-InGaAsP (on InP) well incorporating potential ‘spikes’ and
having the same wavelength can be much wider. The wider well, possible with well shaping, results
in a lower value for three-dimensional (3D) carrier density at a given value of modal gain. For low
loss lasers, this implies a reduction in Auger (and hence total) threshold current to a value below the
best obtainable in a laser based on a square quantum well