Polymer waveguides are successfully fabricated by a simple method, which is incorporated with a lithography-galvanic (LIGA)-like and micromolding process. The refractive index of the UV polymer used in these experiments is changed by an extremely low electric field. The measured propagation loss is 0.32 dB/cm for 1.3 µm and 0.30 dB/cm for 1.55 µm. This process is easy, simple, and suitable for mass production.
We have developed a soft lithography method to replicate polymer waveguides. In this method, the waveguides are produced by a two-step molding process where master mold is first formed on a negatively tone phototresist and subsequently transferred to a PDMS mold, and silicone rubber mold is then used as a stamp to transfer the final waveguide pattern onto a UV cure epoxy. Initial results show good pattern transferring in physical shape. The optical performance is measured based on the propagation loss. In our design, the measurement was measured at 0.26 dB/mm for 1.3μm and 0.24 dB/mm for 1.55μm.
In this talk, we propose a novel tunable optical add/drop multiplexer (OADM), based on Asymmetric Bragg Coupler (ABC) and the liquid crystal as the active layer material. The asymmetric Bragg coupler is made of OG series polymer ridged waveguide. The liquid crystal is filled to cover the waveguide structure, which sandwiches between upper and bottom electrodes. When the external voltage applied, the index of liquid crystal changes to adjust effective index of coupler and inherently tunes the transmission spectrum of the device precisely. The transmission bandwidth is about 32.5GHz, and the tunable range is about 250GHz centered at 1.55nm.
The design and simulation of a new optical add-drop multiplexer (OADM) made of two pairs of grating-frustrated directional couplers is presented. Design theory and simulation are introduced to support is feasibility. The directional couplers are proposed to use polymeric waveguides as the cores. The inverted-ridge waveguide fabrication is proposed using lithography and etching process. The proper dimensions and parameters of each waveguides for OADM are simulated. The designed OADM is 1550 nm wavelength with add-drip filters, bandwidth 20 nm, and 80% peak transmissions showing the application for wavelength division multiplexing (WDM).
A set of grating-frustrated directional couplers is proposed here for wavelength division multiplexer (WDM). Instead of using optical fiber, integrated polymer waveguides with inverted-ridge structure was used in this design. This device is composed of two cascaded directional couplers. Each of the directional coupler is made up of two waveguides with the index of one of the waveguides being a periodic function of z which is the direction of propagation. The average index of the grated waveguide should be equal to that of the un-graded waveguide. According to the coupled wave theory, only the light with a specific wavelength will pass through the waveguide without grating while all other light will be coupled to the grated waveguide when the mixed light is initially input at the un-grated waveguide. This phenomenon is call Bragg reflection and the specific wavelength is called Bragg wavelength. The Bragg wavelength is proportional to the period of the index grating. Therefore, this device is capable of selecting at least three different wavelengths. A detailed analysis of this design is also included in this paper.
In this paper, we have demonstrated two types of polymer waveguide switches with nematic liquid crystal cladding. Although the higher propagation loss in LC materials hinders them from serving as the waveguide film, it has been common that LC exhibiting a large optical anisotropy and an electrically controllable molecular alignment are applied to investigations of slab-waveguide cut off switching as active medium claddings. For this type of switching geometry, a higher contrast ratio is obtainable because simple TE or TM polarized waves may be supported in the planar polymer waveguide.
We propose a wavelength-insensitive optical TE-TM polarization mode converter using twist nematic liquid crystal cell for multi-mode or single-mode fiber communication systems application. Based on the simple and widely used TNLC cell structure, the optical converter has the potential advantages such as inexpensive, simple fabrication processes, and easy mass production. The low crosstalk of -28.3 dB is obtained.
In consideration of better confinement of optical field and integration with practical communication network of optical fiber, we proposed a novel vertical (Delta) (kappa) directional coupler switch with inverted rib waveguides made of nematic liquid crystals (NLCs). Because of the large birefringence of LC's, a very short switching length, about 60 micrometers , is obtained; furthermore, the high extinction ratio, 25.73 dB, can be achieved in the 3D switch.