Partial Parabolic Single Layer Crossing for Silicon-on-Insulator Nanophotonic Waveguides

Improving transmission of partial parabolic single layer crossing for silicon-on-insulator nanophotonic waveguides by composite subwavelength structures

“…E field distributions. (a) Tapered BSWG and DPHs on PPSLC (FOM = 98.72%, T=98.72%, R=5.12×10−6, C=3.29×10−7=−65 dB), (b) PPSLC (FOM = 97.80%, T=97.90%, R=0.001, C=6.27×10−7=−62 dB) 15 …”

“…For a 1% transmission penalty (drop 1% from the highest transmission), the PPSLC has a tolerance of ±10 nm, 15 but the PPSLC with the tapered BSWG and DPHs has a lower tolerance between −4 and +12 nm, as shown in Fig. 12 and Table 3.…”

“…The character of high-transmission, low-loss, and low-crosstalk is the goal of crossings design 1 – 15 …”

“…presented a double layer parabolic taper crossing (DLPTC) of which the footprint was 6×6 μm2 with the transmission of 97.5% and crosstalk of −40 dB; its upper expanded crossing shape reduced the diffraction losses in the crossing and the lateral refractive index contrast; the lower index contrast reduced the diffraction and back reflections in the nonconfined region. Shih et al 15 . presented a partial parabolic single layer crossing (PPSLC) of which the footprint was 6×6 μm2 with the transmission of 97.9% (in the cited reference, transmission = FOM=T−R=97.8%) and crosstalk of −62 dB.…”

“…The character of hightransmission, low-loss, and low-crosstalk is the goal of crossings design. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Many types of crossings have been proposed, such as crossings with multimode interference (MMI), [1][2][3][4] direct, [5][6][7][8][9][10][11] and subwavelength (SW) structures. [12][13][14] The self-imaging property is utilized to reduce the device loss of MMI due to focusing at the center of the crossing.…”