Compact 1×4 multimode interference splitter with tapered sections has been designed and fabricated based on deoxyribonucleic acid-cetyltrimethylammonium biopolymer material. A multistep processing and reactive ion etching technique have been developed to fabricate the device. There is excellent agreement between experimental and theoretical results and the splitter exhibits low excess loss, negligible polarization dependent loss, and well output uniformity for both TE and TM modes at 1550 nm wavelength.

Optical switches are important in signal routing and switching. In this paper, a thermal optical switch with trapezoidal air trenches is proposed. The proposed structure consists of two cascaded 4 × 4 multimode interference (MMI) couplers. The beam propagation method is used to optimize the dimension and analyze the characteristics. Simulation results show excess loss (EL) and insertion loss (IL) are less than 0.14 dB and 0.22 dB at the wavelength of 1550 nm, respectively. Besides, the extinction ratio (ER) is higher than 21 dB. This design has the advantages of small size, low loss, and high flexibility, which is promising for application to all-optical network routing.

A three-dimensional polymer mode (de)multiplexer based on mode evolution is proposed. The proposed configuration is mainly composed of cascaded two tapered couplers where waveguides with different heights are inversely tapered to achieve mode conversions of the E 11 , E 21 , and E 31 modes. The dimensional parameters and characteristics are analyzed by the beam propagation method. This mode (de)multiplexer exhibits the coupling ratio greater than 0.97, excess loss lower than 0.15 dB and extinction ratio higher than 20 dB for TE and TM polarizations over the wavelength range 1530 ∼ 1625 n m (the C + L band). This design has weak wavelength dependence and polarization dependence, which is promising to be applied to broadband on-board mode multiplexing.