Limits...
Optimizing SOI slot waveguide fabrication tolerances and strip-slot coupling for very efficient optical sensing.

Passaro VM, La Notte M - Sensors (Basel) (2012)

Bottom Line: In particular, we have focused on Silicon On Insulator (SOI) technology, representing the most popular technology for this kind of devices, simultaneously achieving high integration capabilities, small dimensions and low cost.An accurate analysis of single mode behavior for high aspect ratio slot waveguide has been also performed, in order to provide geometric limits for waveguide design purposes.Finally, the problem of coupling into a slot waveguide is addressed and a very compact and efficient slot coupler is proposed, whose geometry has been optimized to give a strip-slot-strip coupling efficiency close to 100%.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Elettrotecnica ed Elettronica, Politecnico di Bari, Bari, Italy. passaro@deemail.poliba.it

ABSTRACT
Slot waveguides are becoming more and more attractive optical components, especially for chemical and bio-chemical sensing. In this paper an accurate analysis of slot waveguide fabrication tolerances is carried out, in order to find optimum design criteria for either homogeneous or absorption sensing mechanisms, in cases of low and high aspect ratio slot waveguides. In particular, we have focused on Silicon On Insulator (SOI) technology, representing the most popular technology for this kind of devices, simultaneously achieving high integration capabilities, small dimensions and low cost. An accurate analysis of single mode behavior for high aspect ratio slot waveguide has been also performed, in order to provide geometric limits for waveguide design purposes. Finally, the problem of coupling into a slot waveguide is addressed and a very compact and efficient slot coupler is proposed, whose geometry has been optimized to give a strip-slot-strip coupling efficiency close to 100%.

No MeSH data available.


Related in: MedlinePlus

(a) Γc (%) versus tox and g, with H = 220 nm and W = 210 nm; (b) Γc (%) versus tair and g, with H = 220 nm and W = 210 nm.
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f4-sensors-12-02436: (a) Γc (%) versus tox and g, with H = 220 nm and W = 210 nm; (b) Γc (%) versus tair and g, with H = 220 nm and W = 210 nm.

Mentions: Nowadays, waveguide sidewall roughness is an important aspect to be considered for reducing the optical losses, requiring critical control of technological process. Using optimized SOI technology processes, sidewall roughness with standard deviation as low as 1.5 nm and correlation length of 13 nm can be successfully achieved [20,21]. Moreover, deposition of an additional oxide layer or thermal oxidation has been demonstrated in a number of works to mitigate the light scattering loss at the roughness [22]. Due to this reason, the effect of an oxide layer, a few nanometers thick (tox), on the structure top has been expressly discussed and optimized in the paper. The additional oxide layer has obviously the effect to reduce the sensitivity since it fills part of the gap region, simultaneously decreasing the refractive index contrast with respect to the silicon wires. Figure 4(a) shows that the influence of the oxide layer could be mitigated by increasing the slot width. The Ψtox coefficient is −0.4922 %/nm, calculated for g = 120 nm, while a value of −0.3601 %/nm can be achieved for g = 160 nm.


Optimizing SOI slot waveguide fabrication tolerances and strip-slot coupling for very efficient optical sensing.

Passaro VM, La Notte M - Sensors (Basel) (2012)

(a) Γc (%) versus tox and g, with H = 220 nm and W = 210 nm; (b) Γc (%) versus tair and g, with H = 220 nm and W = 210 nm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376618&req=5

f4-sensors-12-02436: (a) Γc (%) versus tox and g, with H = 220 nm and W = 210 nm; (b) Γc (%) versus tair and g, with H = 220 nm and W = 210 nm.
Mentions: Nowadays, waveguide sidewall roughness is an important aspect to be considered for reducing the optical losses, requiring critical control of technological process. Using optimized SOI technology processes, sidewall roughness with standard deviation as low as 1.5 nm and correlation length of 13 nm can be successfully achieved [20,21]. Moreover, deposition of an additional oxide layer or thermal oxidation has been demonstrated in a number of works to mitigate the light scattering loss at the roughness [22]. Due to this reason, the effect of an oxide layer, a few nanometers thick (tox), on the structure top has been expressly discussed and optimized in the paper. The additional oxide layer has obviously the effect to reduce the sensitivity since it fills part of the gap region, simultaneously decreasing the refractive index contrast with respect to the silicon wires. Figure 4(a) shows that the influence of the oxide layer could be mitigated by increasing the slot width. The Ψtox coefficient is −0.4922 %/nm, calculated for g = 120 nm, while a value of −0.3601 %/nm can be achieved for g = 160 nm.

Bottom Line: In particular, we have focused on Silicon On Insulator (SOI) technology, representing the most popular technology for this kind of devices, simultaneously achieving high integration capabilities, small dimensions and low cost.An accurate analysis of single mode behavior for high aspect ratio slot waveguide has been also performed, in order to provide geometric limits for waveguide design purposes.Finally, the problem of coupling into a slot waveguide is addressed and a very compact and efficient slot coupler is proposed, whose geometry has been optimized to give a strip-slot-strip coupling efficiency close to 100%.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Elettrotecnica ed Elettronica, Politecnico di Bari, Bari, Italy. passaro@deemail.poliba.it

ABSTRACT
Slot waveguides are becoming more and more attractive optical components, especially for chemical and bio-chemical sensing. In this paper an accurate analysis of slot waveguide fabrication tolerances is carried out, in order to find optimum design criteria for either homogeneous or absorption sensing mechanisms, in cases of low and high aspect ratio slot waveguides. In particular, we have focused on Silicon On Insulator (SOI) technology, representing the most popular technology for this kind of devices, simultaneously achieving high integration capabilities, small dimensions and low cost. An accurate analysis of single mode behavior for high aspect ratio slot waveguide has been also performed, in order to provide geometric limits for waveguide design purposes. Finally, the problem of coupling into a slot waveguide is addressed and a very compact and efficient slot coupler is proposed, whose geometry has been optimized to give a strip-slot-strip coupling efficiency close to 100%.

No MeSH data available.


Related in: MedlinePlus