Self-aligned oxidised porous silicon optical waveguideswith reduced loss

Abstract

A report is presented into the fabrication of self-aligned oxidised porous silicon optical waveguides, the optical losses of which at both visible and infrared wavelengths are significantly reduced, to around the 1 dBcm(-1) limit widely considered as critical for application success

Recent progress in integrated waveguides based on oxidized porous silicon

“…Variation of ±0.02 dB for the output signal due to inaccurate tuning and noise of the system was established by multiple measurements. The measurements made by this new method are in a good agreement with previously used techniques such as ''cut-off'' method and fiber probe scanning [4][5][6][7][8].…”

“…CZ silicon Sb-doped Si (1 0 0) wafers of 0.01 X cm resistivity were used. Process previously designed and described in [7,10], did not consider the negative influence of swirl-defects in the guiding properties. Fabrication process includes the following basic operations: chemical cleaning in RCA solutions, silicon nitride deposition, photolithography, plasma chemical etching of silicon nitride, two-step anodization, silicon nitride removal, chemical cleaning, and thermal oxidation of PS.…”

“…Fig. 4 shows optical photograph of the OPS waveguide fabricated by the process described in [7,10]. The dark regions within the WG are the uncompleted oxidation of PS which cause a drastic increase in optical losses and the white regions represent the PS completely oxidized.…”

“…The modulation of the anodization process allows to modify the porosity of the initial PS and final OPS obtaining the refractive index jump between the core and the cladding layer. Low optical losses are essential to achieve optical integrated WG and by optimizing the fabrication process optical losses were decreased, first from 10 dB/cm to 3-5 dB/cm for P + -type silicon [4,5], and then down to 1 dB/cm for N + -type silicon [7,8]. Recently, a two-step anodization process has been developed and planar losses of 0.5 dB/cm in the visible range have been demonstrated [9].…”

Photoluminescence from erbium incorporated in oxidized porous silicon

“…Recently, a planar optical waveguide based on OPS was demonstrated [6,7] showing also that is compatible with the conventional microelectronic technology. OPS waveguides are presently passive devices and incorporating rare-earth element Er into OPS offers a way to realize optical planar waveguide amplifiers operating at the third telecommunication window (i.e.…”