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

Coupling efficiency versus hmin for the proposed strip-slot-strip coupler (in the inset), as calculated by 3D FDTD.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3376618&req=5

f13-sensors-12-02436: Coupling efficiency versus hmin for the proposed strip-slot-strip coupler (in the inset), as calculated by 3D FDTD.

Mentions: In order to estimate the coupling efficiency, we have considered a slot waveguide with both an input and output coupler (see the inset in Figure 13). The coupling efficiency has been calculated as [14]:(9)η=PoutPinwhere Pin is the power launched in the input waveguide and Pout is the power leaving the output waveguide. Both BPM and FDTD full vectorial 3D simulations [23] have been used to simulate this device, evaluating a coupling efficiency which approaches 100% in both cases. With reference to Figure 12, the influence of a silicon etching residue at the starting section of the Y-branch can be estimated by taking into account the value of hmin in the optimization process. In fact, we have observed that this is the most important parameter affecting the coupling efficiency of the device. It is intuitive that the optimum situation can be achieved with hmin = 0, which cannot be easily obtained in practical fabrication process. However, properly optimizing the taper length and the input waveguide width, it can be possible to reduce the influence of hmin on the coupling efficiency at values less than 2%. We have demonstrated that, for a taper length of 4 μm and hmin ≤ 50 nm, the coupling efficiency never decreases under 98% (see Figure 13). Moreover, the coupling efficiency still remains very high (80%) in case of abrupt transition between strip and slot region (hmin = g = 120 nm). In Table 4 the values of cladding power confinement factors are summarized for designed strip-slot coupler, as calculated by 3D FDTD and BPM simulations. and compared with values estimated by a full vectorial 2D FEM analysis.


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

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

Coupling efficiency versus hmin for the proposed strip-slot-strip coupler (in the inset), as calculated by 3D FDTD.
© Copyright Policy
Related In: Results  -  Collection

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

f13-sensors-12-02436: Coupling efficiency versus hmin for the proposed strip-slot-strip coupler (in the inset), as calculated by 3D FDTD.
Mentions: In order to estimate the coupling efficiency, we have considered a slot waveguide with both an input and output coupler (see the inset in Figure 13). The coupling efficiency has been calculated as [14]:(9)η=PoutPinwhere Pin is the power launched in the input waveguide and Pout is the power leaving the output waveguide. Both BPM and FDTD full vectorial 3D simulations [23] have been used to simulate this device, evaluating a coupling efficiency which approaches 100% in both cases. With reference to Figure 12, the influence of a silicon etching residue at the starting section of the Y-branch can be estimated by taking into account the value of hmin in the optimization process. In fact, we have observed that this is the most important parameter affecting the coupling efficiency of the device. It is intuitive that the optimum situation can be achieved with hmin = 0, which cannot be easily obtained in practical fabrication process. However, properly optimizing the taper length and the input waveguide width, it can be possible to reduce the influence of hmin on the coupling efficiency at values less than 2%. We have demonstrated that, for a taper length of 4 μm and hmin ≤ 50 nm, the coupling efficiency never decreases under 98% (see Figure 13). Moreover, the coupling efficiency still remains very high (80%) in case of abrupt transition between strip and slot region (hmin = g = 120 nm). In Table 4 the values of cladding power confinement factors are summarized for designed strip-slot coupler, as calculated by 3D FDTD and BPM simulations. and compared with values estimated by a full vectorial 2D FEM analysis.

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