Christian Duchet

Recent Developtents In Optically Nonlinear Polymers And Related Electro-Optic Devices

Side chain polymers, containing hyperpolarizable moieties as pendant groups, have been applied as optically nonlinear materials. Electro-optic properties have been induced via electric field poling of nultilayer structures incorporating the nonlinear polymers. For a poling field strength of 156 Wpm, the obtained i r33 coefficient was equal to 28 pn/V at the wavelength of 1.3 pm, which is close to r33 = 32 of the inorganic single crystal lithium niobate. Low loss mcnomode charnel waveguides (< 1 dB/cm @ 1.3 μm wavelength) have been realized in the optically nonlinear polymer nultilayers. Tunable Fabry-Perot etalons, monamode phase and intensity modulators and monomode Mach-Zehnder interferameters, have been made and tested; their performances will be discussed. Owing to their considerable electro-optic coefficients and attractive processing properties, polymers are becoming serious alternatives for the currently often applied lithium niobate.

Optically nonlinear polymeric switches and modulators

Side chain polyrrers containing hyperpolarizable noieties as the periant groups have been applied as optically ncrilinear traterials to produce polyxreric integrat1 electro-optical devices . Phase nixiulators, intisity nixiulators (1ch-Zebzx1er interferaiters) aixi optical 2*2 sce switches ( 2*2 directixa1 nixie couplers) have been uncle . Driving voltages as 1ci as 2 Volts (V ) have been obtain1 for a 24 nm active 1gth çkmse ncdulator; 4.4 Volts (V ) for a 14 inn active 1angthch-Zebrx1er interferarter, ath 9 Volts for a 14 nm active length directionI node ccupler. Intisity nixiulation ratios of about -23 dB atti -17 dB have been derived for the intensity nixiulator atd nixie ccxipling switch, respectively. The device properties , theni.l arxi electrical stabilities , etc. will be discussed. The results obtained shcw that optically txnlinear polyiTers are attractive caixlidates for the realizaticzi of polyireric integrated electro-optical devices. In additicn, several passive veguiding devices have beai nnde.

Optically nonlinear polymeric devices

Optically nonlinear side chain polymers have been used to make a number of polymeric electro-optic and thermo-optic switching devices. The following devices are described and their performances discussed: a 2 X 2 electro-optical directional mode coupler; a 1 X 2 Mach-Zehnder switch comprising a Y-splitter combined with 2 parallel arms and a directional coupler section; a polarization and wavelength independent switch comprising a Y- junction; and an electro-thermo-optical Mach-Zehnder interferometer. In addition, the stability of some of the devices is presented and discussed. The directional mode coupler shows -17 dB modulation depth for 7.5 Volts switching voltage; the Mach-Zehnder switch required 10 Volts for 14 dB switching ratio; the Y-junction switch needed 50 mW for >20 dB modulation; the electro-thermo-optical Mach-Zehnder required as low as 0.5 mW to achieve (pi) -phase shift. The results show that optically nonlinear side chain polymer are attractive materials for the realization of polymeric switching devices.

Polymeric Guided Wave Optics

Interest in organic electro-optic materials for integrated optics has been increasing with the realisation of improved electro-optic co-efficients for these systems. Incorporation of active organic molecules as side groups on a polymer backbone seems to be the best method of achieving a poled polymer film with properties suitable for planar processing techniques. Channel Waveguide manufacture has been achieved on a number of substrate materials using such a polymer system with waveguide losses of less than 1 dB/cm. Active components have been fibre pigtailed and packaged with a Vpi of less than 10 volts. A review of the technologies for preparing such components will be given along with an assessment of the further applications and developments envisaged with these materials. Comparison will be made with currently available integrated optical components, critically assessing the state of the technology.

Thermal Stability Of LiNbO 3 Electro-Optic Waveguide Modulators For Remote Voltage Sensing

The thermal instability of the working point of integrated devices may arise from photoelastic effect. MACH-ZEHNDER interferometer with special electrode structure, previously designed to have a high voltage sensitivity, leads also to a good thermal stability.

New integrated optic TE/TM splitter made on LiNbO3 isotropic cut

A new TB/TM integrated polarization splitter made on LiNbO3 for an isotropic cut (X cut with z propagating light) has been theoretically studied and experimentally tested. The anisotropic behaviour is introduced via the electro-optic effect which acts differently on each polarization. At 1. 3 m wavelength a polarization extinction ratio of 25dB has been obtained.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.