Wyniki wyszukiwania - BazTech

1

Multiple omnidirectional reflection bands from half-wave layered periodic structures

Cojocaru E.

Optica Applicata

|

2005

|

Vol. 35, nr 2

201-207

EN

The paper is concerned with one-dimensional multilayers that exhibit multiple bands of omnidirectional reflection, which means complete reflection regardless of incidence angle and polarization. The typical quarter-wave constraint is replaced by the stipulation that a pair of adjacent layers should have a total optical thickness of one half of wavelength. Simple approximate analytic expressions are derived for the multiple bandgaps of the half-wave periodic structures.

2

Second and third order dispersion of broadband thin-film antireflection coatings for ultrafast lasers

Cojocaru E.

Optica Applicata

|

2004

|

Vol. 34, nr 1

25-29

EN

Ultrashort pulse generation relies on a high quality of the laser cavity dispersion control. Common dielectric thin-film coatings, the broadband antireflection (AR) coatings being included, may introduce great fluctuations on the group delay dispersion (GDD) and the third order dispersion (TOD) of the reflected pulse. By accumulation in time, these fluctuations may contribute to the alteration or the cease of the ultrafast regime, especially in ring laser resonators. With an insignificant computational effort, optimized broadband AR coatings may be designed to provide near-zero values of the GDD and the TOD at the expense of poor AR quality.

3

Temporal pulse response of quasi-periodic Fibonacci Fabry-Perot type optical filters

Cojocaru E.

Optica Applicata

|

2002

|

Vol. 32, nr 1-2

85-92

EN

A specific behaviour of quasi-periodic multilayers is the existence of isolated peaks inside the forbidden transmission gap. Thus, quasi-periodic multilayers may be an alternative to the periodic structures with defects. The compressing capacity of quasi-periodic Cantor filters has been presented by other authors. We analyse comparatively the compressing capacity of quasi-periodic Fibonacci (F) and Fibonacci Fabry-Perot (FFP) multilayers at normal incidence. Various pairs of nondispersive layer refractive indices and different embedding media are considered. Symmetrical FFP multilayers admit wider ranges of layer refractive indices at which parameters characterising the compressing capacity attain certain levels

4

Equivalence relations for the enhanced polar Kerr effect at normal incidence.

Cojocaru E.

Optica Applicata

|

2000

|

Vol. 30, nr 2-3

415-419

EN

An enhancement of the oilar Kerr effect in the magneto-optical (MO) readout system is achieved by specific dielectric thin-film coatings. The MO medium of referactive index n and MO constant q, overcoated by dielectric thin film, is equivalent in normal reflection to an uncoated MO medium of parameters N and Q. Following this reasoning we present simple relations for equivalent parameters N and Q of different systems. Behaviour of parameters N and Q is illustrated by numerical examples. The use of equivalent parameters allows an easier comparison among different MO systems.

5

Material relations for malism for the polar Kerr-effect multifilm and bulk systems at oblique incidence.

Cojocaru E.

Optica Applicata

|

1999

|

Vol. 29, nr 4

601-610

EN

A simplified matricial formalism for the polar Kerr-effect multifilm and bulk systems at oblique incidence is presented. Overall 4x4 characteristic matrices are determined for multifilms comprising both dielectric and magnetooptic thin layers having their boundaries placed into the ambient isotropic medium. Then 2x2 extended Jones reflection matrices are obtained for polar Kerr-effect multifilm and bulk systems. Numerical examples of Kerr rotation angle and figure of merit function variations against the incident angle are given comparatively for p-and s-polarized incident light.