قياس وتحليل الخسائر لموجات الموجع ذوات الفتحة المصنعة من سليكون على عازل == Measurements and Analysis of The Losses for Fabricated SOI Slot Waveguides
Author name:
ميثم نعيم صالح
Supervisor name:
مازن مانوئيل الياس
General topic:
Laser Science
Specific topic:
Laser Applications in Electronics and Communications Engineering
Degree:
Doctorate
University:
University of Baghdad - Laser Institute For Postgraduate Studies
Language:
English
University location:
Baghdad
First pages:
29T201 - p.pdf
Abstract:
An interesting silicon photonics component is the slot waveguide. The discontinuity of the normal component of the displacement vector can be used to affect guiding of the majority of the electric field energy in a narrow low index gap when the field is polarized parallel to the silicon surface, that is, perpendicular to the silicon confining walls. By infiltrating nonlinear material into such a gap, one can simultaneously confine electric and optical fields achieving a high efficient optical modulation or switching that is becoming more desirable on optical communication. An array of 200 Silicon - on - Insulator (SOI) slot waveguide devices of varying slot widths, ribs widths, taper lengths and slot lengths are fabricated in each cell of a wafer fabricated at a commercial foundry. The cells are cleaved into individual chips after fabrication. Some chips are coated with thin films of polymers that fully infiltrated the slots. Measurements that consisted on spectral loss are made on the grating coupler waveguide devices of both coated and uncoated chips. Individual devices exhibited insertion losses varying from several dB up to values so great that the response is below the noise floor of the optical spectrum analyzer employed as a receiver. The chips that failed in the transmission test are primarily uncoated ones. Nominally identical devices on different chips exhibited nominally identical behavior. A commercial software program is used to simulate each of the structures that is included in the 200 devices test. The simulations are seen to show a degree of qualitative agreement with the experimental results. Comparison of the experimental measurements and the simulation results indicates that the loss inherent in a slot waveguide is quite low. Near loss free couplers from ridges to slots are achievable in case of coated devices, whereas the situation is different in case of uncoateddevices where a lot of energy is dissipated through the substrate. Use of a surface roughness model indicates that the excess loss that slots exhibit with respect to a ridge mode counterpart arise almost solely from surface scattering off the surface roughness. The increased loss in the case of the slot guide arises from the higher electromagnetic energy density at the surface of the guide due to the electric field discontinuity that is employed as a guidance mechanism in slot modes in contradistinction to ridge modes that are index - guided. Conclusions include some speculation as to the limits on the loss that can be achieved by variation the design of slot guides without any improvement in surface roughness over what is now available with fabrication in commercial foundries.
