Planar microcavity

Figure 141 shows the EL spectra from a microcavity (a) and conventional LED (b) based on the emission from an NSD dye forming a thin emitting layer of a three-organic layer device. It is apparent that the half-width of emission spectra from the diode with microcavity is much narrower than those from the diode without cavity. With 0 = 0°, for example, the half-width of the spectrum of the diode with cavity is 24 nm whereas that of the sample without cavity increases to 65 nm. According to Eq. (275), the resonance wavelength, A, decreases with an increase of 0 in agreement with the experimental data of Fig. 141. We note that no unique resonance condition in the planar microcavity is given due to broad-band emission spectrum of the NSD emission layer. Multiple matching of cavity modes with emission wavelengths occurs. Thus, a band emission is observed instead a sharp emission pattern from the microcavity structure as would appear when observed with a monochromator the total polychromic emission pattern is a superposition of a range of monochromatic emission patterns. The EL spectra...

FIGURE 4.1. Structures of two types of microcavities (a) planar microcavity and (b) microdisk. 

Fig. 4.3b illustrates the modifications to the free-space emission produced by the planar microcavity device whose structure is shown schematically in Fig. 4.3a. The principal effect is a narrowing of the emission spectmm in most directions. The cavity device spectrum is taken along the cavity axis, and the full width at half-maximum (FWHM) is lowered from 100 nm for a noncavity device to 18 nm. With higher- Q cavities, it is possible to get narrower spectra, and Tokito et al. have reported LEDs with a FWHM of 8 nm.28...

Single Mode and Multimode Planar Microcavity LEDs... 

FIGURE 4.4. Schematic structure of a patterned planar microcavity in which the Si3N4 filler layer is etched to three different thicknesses to change the optical thickness. The step heights are 40 nm, which is sufficient to change the resonance position by 45-60 nm. 

The effects produced by a planar microcavity on the electroluminescence characteristics of organic materials have been described. A number of organic and polymeric semiconductors have been employed by various groups in studies on microcavity LEDs. However, for detailed descriptions, three categories of emissive materials have been considered undoped Alq, Alq doped with 0.5% pyrromethene, and Alq+NAPOXA. Alq has a broad free-space emission spectrum spanning the... 

Finding polariton states in disordered planar microcavities microscopically is a difficult task which do not attempt here. As a first excursion into the study of disorder effects on polariton dynamics, here we will follow (32) to explore the dynamics in a simpler microscopic model of a ID microcavity. Such microcavities are interesting in themselves and can have experimental realizations from the results known in the theory of disordered systems (39) one can also anticipate that certain qualitative features may be common for ID and 2D systems (38). 

See also Agranovich, V. M., Basko, D. M., La Rocca, G. C., and Bassani, F. (1998). J. Phys. Gondens. Matter 10, 9369, and Basko, D. M. (2003). Electronic energy transfer in a planar microcavity. In Thin Films and Nanostructures. Electronic Excitations in Organic Based Nanostructures 31, edited by V. M. Agranovich and G. F. Bassani. Elsevier, Amsterdam, pp. 403-446. 

A Fainstein, B Jusserand, V Thierry-Mieg. Raman-scattering enhancement by optical confinement in a semiconductor planar microcavity. Phys Rev Lett 75 3764-3767, 1995. 

Rigneault H., Monneret S. Modal analysis of spontaneous emission in a planar microcavity. Phys. Rev. A 1996 54 2356-2368... 

G. Bjork, On the spontaneous lifetime change in an ideal planar microcavity—transition from a mode continuum to quantized modes, lEEEJ. Quant. Electron. 50 2314 (1994). 

PBG effects have been observed in two-photon polymerized PhCs [15]. The research was naturally extended towards the formation of planar microcavities by introducing defects into the logpile PhC (Fig. 50a). The fabricated structure [17] consisted of 20 layers of rods. The planar defect was introduced by skipping the exposure of every other rod in the tenth layer, located in the middle of the PhC structure. This was simply accomphshed by closing the laser beam while drawing the particular fines. 

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