Suspended polarization beam splitter on silicon-on-insulator

Abstract

Polarization handling in suspended silicon photonics has the potential to enable new applications in fields such as optomechanics, photonic microelectromechanical systems, and mid-infrared photonics. In this work, we experimentally demonstrate a suspended polarization beam splitter on a silicon-on-insulator waveguide platform, based on an asymmetric directional coupler. Our device presents polarization extinction ratios above 10 and 15 dB, and insertion losses below 5 and 1 dB, for TM and TE polarized input, respectively, across a 40 nm wavelength range at 1550 nm, with a device length below 8 µm. These results make our suspended polarization beam splitter a promising building block for future systems based on polarization diversity suspended photonics.

Complete Single Mode Condition for Silica-Titania Rib Waveguides on Glass Substrates

“…9) even though the first derivative of 01 cff u varies significantly with increasing values of the parent slab thickness H. The intervals of r-values in which HE01 and EH01 modes are leaky, belong to the interval (3). Values of the approximation error, E, were calculated by using (6). They are presented as a functions of the parent slab thickness, H, in Figs 10 and 11.…”

“…The particularly big difference exists for the coefficient a of the S(r) of the EH00 mode. The more comprehensive picture is unfolded on a characteristic of the approximation error (6), which is shown in Fig. 17.…”

“…They are a part of many planar integrated circuit (PIC) designs. Single mode propagation is favorable, or even necessary, considering devices that are designed for application in integrated optic telecommunication systems, [5,6] quantum communication applications [7] and integrated optic chemical and biochemical sensor systems [8][9][10], especially those which use the evanescent wave spectroscopy technique [11,12]. Limiting our attention to devices belonging to the second group, it is interesting to note that rib waveguides are being used two different ways.…”

Compact low-birefringence polarization beam splitter using vertical-dual-slot waveguides in silicon carbide integrated platforms

“…The polarization beam splitter (PBS), a key component for polarization manipulation, enables two orthogonal mode separation and provides polarization diversity in photonic integrated circuits, which can also be applied for the polarization division multiplexing and the polarization entanglement quantum systems [10,11]. Many different types of PBSs have been studied in silicon-on-insulator integrated platforms, for example, directional couplers, multimode interferometers, gratings, and plasmonic waveguides [12][13][14][15][16][17]. Although silicon (n = 3.5 at 1550 nm) does not have material-based birefringence, high geometric birefringence in silicon waveguides makes easy polarization beam splitting, as the phase-matching condition cannot be satisfied by two orthogonal modes simultaneously due to the large effective refractive index contrast.…”

“…Waveguides, made of optical materials with lower refractive index, such as SiC (n = 2.6), silicon nitride (SiN) (n = 2.0) and lithium niobate (LiNbO 3 ) (n = 2.2) at 1550 nm, usually require larger geometry to confine the light, and have lower birefringence, compared to silicon waveguides. For example, the effective refractive index of the fundamental TE and TM modes in a typical standard single-mode silicon waveguide with a dimension of 220 × 500 nm 2 at 1550 nm [13,14], is 2.39 and 1.59, respectively, but becomes 1.79 and 1.63, respectively, in a typical single-mode 4H-SiC waveguide with a dimension of 350 × 560 nm 2 [1], which shows much lower birefringence. Therefore, it is a challenge to make compact and efficient PBSs in the relatively low-refractive-index optical materials based integrated platforms [18].…”