Hyun Nam Yoon

Optical power handling properties of polymeric nonlinear optical waveguides

Polymeric nonlinear optical waveguides of a copolymer of 4‐(N’‐2‐methacroyloxyethyl‐N‐ methyl‐amino)‐4’‐nitrostilbene and methyl methacrylate were tested for optical power handling capability at near‐infrared wavelengths. When exposed to about 5×105 W/cm2 optical power density at 1325 nm wavelength laser light, the waveguide showed a rapid decay of optical transmission on the order of about 3 dB/h. Operation of the waveguides in an oxygen‐free environment significantly reduced the decay rate to greater than 0.25 dB/h. The decay was a result of spatially inhomogeneous change of refractive index distributed along the length of the waveguides. Micrographs showing the photoinduced local variations of refractive index and the resulting loss of optical confinement of the waveguides are presented.

Polymeric Electro-Optic Waveguide Modulator; Materials And Fabrication

In this paper, we are reporting on organic polymeric materials designed for electro-optic waveguide device fabrication and a fabrication method for low loss integrated optical devices. These polymers are methacrylic chain polymers with non-linear optical moieties attached as side chains through variable length spacer groups. Variation of the spacer length allows the tailoring of the phase structure of the polymers as well as the glass transition temperature. For electro-optic device use, the most important material parameter is r3 3 the largest tensor element of the electro-optic tensor. We have developed polymeric materials with r3 3 values as high as 45 pm/V at 1.3 microns (98 pm/V at 632 nm) using an electrical poling process. Additionally, we have characterized optical and electrical properties of the polymer films. Further, a fabrication process for waveguide electro-optic devices from the polymers has been developed and integrated modulators have been built.

Polymeric Integrated Electro-Optic Modulators

Polymeric optical waveguides for integrated optical devices are of current interest for their potential application in very high bandwidth opto-electronic systems. We report our progress in defining and characterising channel waveguides in polymers having large electro-optic coefficients. The waveguide patterns are formed as etched channels in a polymer cladding layer. Further layers deposited onto these channels form 2-dimensional waveguides with monomode characteristics at a wavelength of 1.3 microns. The mode size is controllable and may be optimised for fibre mode coupling to minimise the coupling loss. Electro-optic phase and amplitude modulation is demonstrated for slab and channel waveguides. We report values for the off-resonance electro-optic coefficient in poled polymer films somewhat higher than the largest value in lithium niobate. The implications of such device structures for applications in high performance multi-GHz amplitude modulators are discussed. In particular, the large values of n3r and the near equality of the optical and microwave refractive indices indicates that these polymers will have significant advantage over traditional inorganic materials for wide bandwidth integrated optical modulators.

Polymeric materials for high-speed electro-optic waveguide modulators

This paper discusses some of the important material property requirements for polymeric materials in electro-optic device applications, in particular, a detailed materials characterisation of a promising polymer that is not only high in electro-optic activity after poling, but has predicted long term thermal stability of the poled structure. This material is a methacrylic chain polymer with non-linear optical moieties attached as side chains through a spacer group. Progress in fabrication and characterisation of waveguides using this polymer is also reported.

Polymer-based electro-optic modulators: fabrication and performance

A wide bandwidth Mach-Zehnder modulator with on/off switching powers of 20 dBm, a bandwidth of up to 20 GHz, and insertion losses around 5 dB is presented which is based on HCC-1232 polymer. Attention is given to material properties of HCC-1232, the modulator design, and preliminary test results.