Confinement factor

In modem heterostructure lasers, the actual active layer is usually very thin, much thinner than the optical mode to be supported by its optical gain. Therefore, it is convenient to introduce the so-called optical confinement factor T, which relates the material optical gain gmlt to the net optical gain geff seen by the lasing mode [6] ... 

Depending on the details of the structure, particularly on the confinement factor, the pump power density needed to achieve an effective optical gain of, say, 50 cm 1 is of the order of a few hundred kilowatts per square centimetre at room temperature [14-16],... 

FIGURE 4(a), the relation between device diameter and threshold current is shown. In this estimation, the structure shown in FIGURE 4(b) has been assumed. The transverse optical confinement factor for a cylindrical waveguide with GaN core and AIN cladding was taken into account in this estimation [8,17]. If we can fabricate the device with a diameter less than 10 pm, a GaN-based VCSEL with sub-milliampere threshold currents can be expected. 

When people consider confinement effects, they consider mainly an increase in the encounter probability inside a single pore and therefore, expect an acceleration of the reaction. Such in-pore acceleration has been quantified by Tachiya and co-workers for diffusion-limited reactions through the so-called confinement factor [see Eq. (11.58) in Ref. 40]. From this treatment, confinement effects are expected to disappear when the reaction radius is less than one tenth of the confinement radius. Considering the reaction radii of radiolytic species, no acceleration by confinement should be expected for pore diameter larger than 10 nm. For smaller pore size, acceleration of the recombination reactions within spurs would be critical in the determination of radiolytic yields in the nanosecond time range. However, the existence of such an acceleration of radiolytic reactions has not been suggested in the nanosecond pulse radiolysis of zeolites and has still to be assessed using picosecond pulse radiolysis. 

The RT modal gain (Gmod) is calculated by using the relation where G ax is the peak gain of Fig. 3, Np is the number of "W" or "M" periods taken equal to 5 and Fp is the optical confinement factor per period. Results as a function of carrier concentration Nsd (cm ) are shown in Fig. 4. The 3D carrier concentration is deduced from N3D = N2D / Leff, where Leff is the thickness of one "W" or "M" cell. For a N3D equal to 1.5 10 cm , the modal gain exceeds 50 cm, showing that it would be possible to achieve RT lasing operation. 

The H-Oil process is a high pressure, high temperature hydrocracking process, which uses an ebullated bed of catalyst to convert lower value heavy oils into upgraded higher value products. Deposit formation in the equipment downstream of the H-Oil reactor and high sediment accumulation in heavy fuel oil product streams are confining factors in current attempts to maximize H-Oil unit conversion. 

The confinement factors obtained from this simple ray picture are in good agreement with the experimentally determined values. A more detailed discussion of anti-resonant waveguides was published by Schmidt et... 

Shimizu J, Yamada H, Murata S, Tomita A, Kitamura M, Suzuki A (1991) Optical-confinement-factor dependencies of the K-factor, differential gain, and nonlinear gain coefficient for 1.55 im InGaAs/InGaAsP MQW and strained-MQW lasca. TEF.F. Photonics Technol Lett 3 773-776... 

Another factor that can influence explosive performance is the degree of confinement of the explosive charge. In the equations for detonation pressure and velodty, it is assumed that the charge is totally confined. This means that in the equation no allowance is made for loss of heat or the release of explosive products, In just the reverse of the confinement assumption, the equation assumes that there are no lateral confinements to the passage of the detonation wave. In essence, these confinement factors tend to cause the real world values of detonation pressure and velocity to be less than, those produced by the equations. 

Several methods for the identification of the confined zones have been suggested for partially and fully encased sections, and confinement factors, k, have been developed for use in numerical modeling. According to ECS, the confinement factor, k, is given by ... 

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