In this thesis, on the basis of the phosphor optical models, green and red phosphor mixture optical model has been well established. Under some specific green to red phosphor doping proportions, this model can be utilized to simulate the chromatic properties, spatial CCT distributions, and packaging efficiency. There are some benefits of applying the phosphor optical model, one is that the confusion about mixture or layer phosphor configuration can perform better could be solved. Another is that the comparison and analysis of these phosphor configurations can be made not only in experiment but also in simulation, and will be more details to be discuss in the simulation. There are several types of packaging structures in high color quality applications. Consequently, the importance of phosphor optical model cannot be overestimated. After few steps above and with the help of experimental analysis and optimized in simulation, a packaging structure with high color quality and high efficiency has been approved. Finally, this light source with high performance will be utilized in the luminaire to improve the color and energy saving properties.
We performed the simulation of white LEDs packaging with different chessboard structures of white light
converting phosphor layer covered on GaN die chip. Three different types of chessboard structures are called type 1,
type 2 and type 3, respectively. The result of investigation according to the phosphor thickness show the increasing
of thickness of phosphor layer are, the decreasing of output blue light power are. Meanwhile, the changes of yellow
light are neglect. Type 3 shows highest packaging efficiency of 74.3 % compares with packaging efficiency of type
2 and type 1 (72.5 % and 71.3 %, respectively). Type 3 also shows the most effect of forward light. Attention that
the type 3 chessboard structure gets packaging efficiency of 74.3 % at color temperature of daylight as well as high
saving of phosphor amount. The color temperatures of three types of chessboard structure are higher than 5000 K, so
they are suitable for lighting purpose. The angular correlate color temperature deviation (ACCTD) of type 1, type 2
and type 3 are 6500K, 11500K and 17000K, respectively.
We record a reflection volume hologram with two plane waves in lithium niobate. By heating one corner of the LiNbO3 crystal, it will cause an inhomogeneous temperature distribution in the crystal. The thermal expansion results in small
slight deformation of the volume hologram and then decreases the intensity of diffraction light. We also use the model of
volume hologram being an integrator of the lights emitted from elementary light sources (VOHIL) to calculate the
diffracted field for the linear thermal expansion. The results of experiment and simulation are both shown that the
intensity of diffraction light decreases from the heating corner of the crystal. The change of intensity of diffraction light
is predicted successfully with the model of VOHIL for the thermal expansion.
Solar concentrators using wedge prism with diffractive grating or sawtooth profile mirror are
proposed and studied. The concentrator length-to-thickness ratio can exceed 7 and the maximum
concentration ratios exceed 3.5 for these designs.
Optical analysis of the light extraction based on Monte-Carlo ray tracing in high-efficiency GaN-based LEDs
with use of textured structure is presented. The simulation indicates that the introduction of micro pyramid array with
slanted surfaces can effectively improve the light extraction efficiency. In addition, the light extraction of three types
of LED with or without an epoxy lens is analyzed, where the patterned substrate with pyramid structure arrays is
shown most effective way to increase light extraction efficiency in an encapsulated LED with an epoxy lens.
Dramatic spectral narrowing of normally broad band lasers, Ti:Sapphire,Cr:LiSAF, and alexandrite was achieved by simply replacing the output mirror with a reflective, volumetric Bragg grating recorded in photo thermal refractive (PTR) glass. The output power of each laser was changed very slightly from that obtained using dielectric coated output mirrors with the same output coupling as the Bragg grating while spectral brightness increased by about three orders of magnitude.
In this paper we present calculations of the effects on thermal lensing of bonding undoped host crystal to the ends and edges of edge-pumped slab lasers. Using ray tracing and finite element analysis we simulate the distribution of absorbed pump power, 3D temperature, stress, and surface displacements. We numerically calculate the induced lensing due to thermal and stress gradients, and deformation induced end effects. In slabs with undoped material bonded to the edges through which pump light enters, the induced lensing has an "m"-shaped profile while undoped Brewster ends reduce deformation induced lensing.