Coherent reflection

Fig. 11. Schematic of edge-emitting laser diodes where the arrows represent the direction of laser emission and U represents the active region (a) standard stmcture with cleaved facets for mirrors and (b) distributed feedback (DFB) laser that employs coherent reflection from a grating to generate optical...

The optical setup for time-resolved micro-luminescence measurements is based around an Axiotech 100 HD Zeiss microscope, modified to allow laser injection and fluorescence collection. The sample is observed either under transmission or reflection of polarized white light, or under UV illumination (HBO lamp). A set-up consisting of a dichroic mirror, for the selection of the excitation wavelength, and an objective (Epiplan Neofiuar obj. > 350 nm Ealing/Coherent reflection obj. < 350 nm) is used to focus the laser beam on the sample (spatial resolution over 5 pm with a x50 objective). The lim-... 

Therefore, yr(a ) decays rapidly near a>0, as (a>0 — energy decays below E0, y,(co) increases and ( (- Ef) decreases very rapidly, the radiative rate yr(a>) overwhelming the polariton relaxation below an energy threshold which depends on the crystal thickness and on the temperature.90... 

Coherent reflections at the top and bottom boundaries of the plate give way for a set of standing acoustic waves between the two main surfaces of the plate. Due to the piezoelectric nature of quartz two sets of resonance frequencies exist for each mode, depending on the electrical boundary conditions. The first set corresponds to a plate with open-circuit boundary conditions. From the physical point of view charges will be collected on the electrodes building up a potential difference and hence an electrical field from the electrical point of view the electrodes are unconnected. This resonance is termed anti-resonance in the piezoelectric literature and parallel resonance in electronics literature. The second set of resonance frequencies corresponds to a plate with short-circuit boundary conditions. The electrodes are connected and a potential difference cannot be built up. The respective names are resonance in piezoelectric and series resonance in electronics Hterature. The differences arise from piezoelectric stiffening accompanied by differences in the sound velocity. The anti-resonance (parallel) frequencies of each of the three acoustic modes are completely decoupled giving ... 

As seen from Fig. 2, the interference affects all elements of the reflection matrix. The linear dependence of the width of the intensity peak on the packing density (the curves), discussed in theoretical and experimental studies (see [1 3] and references in [17]), is very noticeable. The examples given in Fig. 2 as well as other calculations not shown here reveal the same dependence on in the other components of the coherent reflection matrix. 

An atomic mirror could be a device of practical importance in applications such as a recombiner in an atom interferometer, for deep focusing (in the form of a concave mirror), and in storage of atoms in an atomic cavity. In all of these potential applications it is essential that the atom mirror be an ideal mirror in that (a) the reflection is specular reflection, and (b) the phase shift introduced by reflection can be determined ( coherent reflection). 

Thus, the procedure is to first find the singular solution of the Lorentz-Lorenz law together with the dispersion relation for the effective wave number Kg, and then to determine the arbitrary constant from the scalar equations (2.190) or (2.191). After the conditional average of the scattered field coefficients has been evaluated, the coherent reflected field can be computed by taking the configurational average of (2.171), i.e.,... 

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