Abstract
For grating periods larger than the excitation wavelength, multiple-grating orders couple incident optical radiation to the surface plasma waves (SPW’s) characteristic of the metal-air interface. For a grating period that is an integral multiple of the wave vector of these surface modes, two resonances become degenerate in coupling angle. There are also permitted diffraction orders at this coupling angle. The vicinity of this multiple-mode coupling resonance, where several free-space electromagnetic modes, as well as two surface modes, arecoupled by different orders of a grating, is known as a minigap region. Not surprisingly, the response surface displays complex dependences on frequency, angle, and grating profile. A detailed experimental and theoreticalstudy is presented of the optical response at 633 nm in the (+1, −2) minigap region forAg filmsdeposited on photolithographically defined 870-nm-period gratings. Measurements of both the 0-order reflectance and the −1-order diffraction are presented for a wide progression of grating depths. The SPW resonances depend on the grating depth, and this variation is used to tune throughthe minigap region for a fixed wavelength and period. Similar measurements are presented for a singlegrating as a function of wavelength through the minigap region. In both measurements the 0-order response shows only a single broad minimum as the resonances approach degeneracy, while the −1-order diffraction shows clearly defined momentum gaps. A simple theoretical model based on the Rayleigh hypothesis is presented that gives a good qualitative picture of the response. The response surfaces are sensitive to the grating profile, and detailedmodeling requires inclusion of higher-order grating components.
| Original language | English |
|---|---|
| Pages (from-to) | 1348-1359 |
| Number of pages | 12 |
| Journal | Journal of the Optical Society of America B: Optical Physics |
| Volume | 8 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 1991 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Statistical and Nonlinear Physics
Cite this
Grating coupling to surface plasma waves. II. Interactions between first-And second-Order coupling. / Zaidi, Saleem H.; Yousaf, M.; Brueck, S. R J.
In: Journal of the Optical Society of America B: Optical Physics, Vol. 8, No. 6, 1991, p. 1348-1359.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Grating coupling to surface plasma waves. II. Interactions between first-And second-Order coupling
AU - Zaidi, Saleem H.
AU - Yousaf, M.
AU - Brueck, S. R J
PY - 1991
Y1 - 1991
N2 - For grating periods larger than the excitation wavelength, multiple-grating orders couple incident optical radiation to the surface plasma waves (SPW’s) characteristic of the metal-air interface. For a grating period that is an integral multiple of the wave vector of these surface modes, two resonances become degenerate in coupling angle. There are also permitted diffraction orders at this coupling angle. The vicinity of this multiple-mode coupling resonance, where several free-space electromagnetic modes, as well as two surface modes, arecoupled by different orders of a grating, is known as a minigap region. Not surprisingly, the response surface displays complex dependences on frequency, angle, and grating profile. A detailed experimental and theoreticalstudy is presented of the optical response at 633 nm in the (+1, −2) minigap region forAg filmsdeposited on photolithographically defined 870-nm-period gratings. Measurements of both the 0-order reflectance and the −1-order diffraction are presented for a wide progression of grating depths. The SPW resonances depend on the grating depth, and this variation is used to tune throughthe minigap region for a fixed wavelength and period. Similar measurements are presented for a singlegrating as a function of wavelength through the minigap region. In both measurements the 0-order response shows only a single broad minimum as the resonances approach degeneracy, while the −1-order diffraction shows clearly defined momentum gaps. A simple theoretical model based on the Rayleigh hypothesis is presented that gives a good qualitative picture of the response. The response surfaces are sensitive to the grating profile, and detailedmodeling requires inclusion of higher-order grating components.
AB - For grating periods larger than the excitation wavelength, multiple-grating orders couple incident optical radiation to the surface plasma waves (SPW’s) characteristic of the metal-air interface. For a grating period that is an integral multiple of the wave vector of these surface modes, two resonances become degenerate in coupling angle. There are also permitted diffraction orders at this coupling angle. The vicinity of this multiple-mode coupling resonance, where several free-space electromagnetic modes, as well as two surface modes, arecoupled by different orders of a grating, is known as a minigap region. Not surprisingly, the response surface displays complex dependences on frequency, angle, and grating profile. A detailed experimental and theoreticalstudy is presented of the optical response at 633 nm in the (+1, −2) minigap region forAg filmsdeposited on photolithographically defined 870-nm-period gratings. Measurements of both the 0-order reflectance and the −1-order diffraction are presented for a wide progression of grating depths. The SPW resonances depend on the grating depth, and this variation is used to tune throughthe minigap region for a fixed wavelength and period. Similar measurements are presented for a singlegrating as a function of wavelength through the minigap region. In both measurements the 0-order response shows only a single broad minimum as the resonances approach degeneracy, while the −1-order diffraction shows clearly defined momentum gaps. A simple theoretical model based on the Rayleigh hypothesis is presented that gives a good qualitative picture of the response. The response surfaces are sensitive to the grating profile, and detailedmodeling requires inclusion of higher-order grating components.
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U2 - 10.1364/JOSAB.8.001348
DO - 10.1364/JOSAB.8.001348
M3 - Article
VL - 8
SP - 1348
EP - 1359
JO - Journal of the Optical Society of America B: Optical Physics
JF - Journal of the Optical Society of America B: Optical Physics
SN - 0740-3224
IS - 6
ER -