Birefringence control using stress engineering in silicon-on-insulator (SOI) waveguides

Silicon photonic waveguides for different wavelength regions

“…The difference between the operating and reference temperature is assumed to be -980 K. Table 1 summarises other material parameters used in our simulations which are identical to those used in [25], where the influence of the top oxide cover was analysed for larger rib waveguides (H=2.2 μm).…”

Design Rules for Single-Mode and Polarization-Independent Silicon-on-Insulator Rib Waveguides Using Stress Engineering

“…To achieve zero birefringence (ZBR) in rib waveguides, an optimization of waveguide dimensions is necessary [16]- [18]. As we are investigating a most common situation where there is an oxide upper cladding, the total birefringence is, however, the sum of the geometrical birefringence and stress-induced birefringence [16].…”

“…To achieve zero birefringence (ZBR) in rib waveguides, an optimization of waveguide dimensions is necessary [16]- [18]. As we are investigating a most common situation where there is an oxide upper cladding, the total birefringence is, however, the sum of the geometrical birefringence and stress-induced birefringence [16]. The structure we analyze in this paper, at the operating wavelength of 1.55 m, is a rib waveguide with the height of 1.35 m, and variable waveguide rib width , etch depth , top oxide cover thickness , and sidewall angle , as shown in Fig.…”

Design of polarization-insensitive SOI ring resonators using cladding stress-induced birefringence and MMI couplers

“…As we have reported previously [6,7], the waveguide birefringence (∆n eff = n eff TM -n eff TE ) is a combination of the geometrical and cladding stress-induced birefringence. For the waveguide dimensions given above, both the ring and the MMI waveguides have a large geometrical birefringence of ∆n eff = -2.65×10 -3 and -5.56×10 -3 respectively, as indicated by the circles in Fig.…”

“…Although only specific coupling ratios are possible using 2×2 MMI couplers, the coupling ratio and overall coupler loss are nearly polarization independent (even though the MMI waveguide itself may have significant birefringence), and the tolerances on coupler dimensions are well within the limits of standard photolithography. We have recently reported on the use of SiO 2 cladding stress induced birefringence to control or eliminate birefringence in SOI waveguides, and experimentally demonstrated polarization insensitive arrayed waveguide grating (AWG) devices using this method [6,7]. We demonstrate here that combining stress birefringence control with MMI couplers can result in a ring resonator design that has very modest fabrication requirements, yet has useful FSR (0.5 nm for the waveguide cross-sections used in this example) and resonance line shapes.…”