Jingsong Zhu

DC biased electro-optic polymer waveguide modulators with low half-wave voltage and high thermal stability

The full potential of second-order nonlinear polymers can be utilized in electro-optic polymer modulators with a DC biased operation scheme to greatly reduce the half-wave voltage. This technique makes use of the total achievable electro-optic coefficient, which can be more than three times the value that is used by the conventional devices of poled electro-optic polymer. As the result of the DC bias and with high-μβ chromophores, a low half-wave voltage of 1.5 V was achieved with 2-cm-long birefringent waveguide modulators at the wavelength of 1.3 μm. Results of a 200°C stability experiment indicate that this scheme also enables electro-optic polymer devices to meet the short-term high-temperature stability requirement because the polymer does not need to be poled prior to high-temperature steps.

Low-Vπ high-thermal-stability electro-optic polymer waveguide modulators using the full potenetial of high-μβ chromophores with a DC bias voltage

The full potential of second order nonlinear polymers can be utilized in electro-optic polymer modulators with a DC biased operation scheme to greatly reduce the V(pi ). This technique makes use of the total achievable electro-optic coefficient, which can be more than three times as high as the residual value after the fast partial relaxation following corona or contact poling. As the result of the DC bias and with high (mu) (beta) chromophores, a low V(pi ) of 1.5 V was achieved with 2 cm long birefringent waveguide modulators at the wavelength of 1.3 micrometer. Results of 200 degrees Celsius stability experiment indicate that this scheme also enables electro-optic polymer devices to meet the stability required for high temperature hermetic sealing because the polymer does not need to be poled before device packaging.

Vertically integrated polymer waveguide device minimizing insertion loss and Vπ

We present design and fabrication considerations for a vertically integrated electro-optic polymer modulator. The hybrid design incorporates both passive and active core segments for optimized transmission and modulation of an optical signal. When compared to traditional structures, this vertically integrated modulator potentially reduces fiber coupling and propagation losses by more than 10 dB for a 6 cm structure while maintaining a minimized V(pi ).

High E-O Coefficient Polymers Based on a Chromophore Containing Isophorone Moiety for Second-Order Nonlinear Optics

Organic second-order nonlinear optical (NLO) materials have been intensely pursued for the past two decades. The superior nonlinearity, along with the inherent ultrafast response and large laser damage threshold, suggests that organic NLO materials are ideal for electro-optic and telecommunications applications. A high-{micro}{beta} chromophore APII utilizing isophorone as {pi}-conjugation bridge was processed into both PMMA guest host and crosslinked (XL) polyurethane network with various loading densities. High electro-optic coefficients, r{sub 33} = 30 pm/V (in PMMA) and r{sub 33} = 32 pm/V (in polyurethane) at 1.06 {micro}m were obtained. Alignment temporal stability ranged from 90 to 120 C for XL polymer network. There is virtually no intrinsic absorption loss at 1.3 {micro}m (solution measurement). Also noteworthy is that high optimum loading densities of this chromophore are attainable in both cases without detectable chromophore aggregation due to intermolecular electrostatic interactions.

Ultrastructure synthesis of special architectures for photonic applications: high-frequency electro-optic modulators and high-density optical memories

A major requirement for polymeric electro-optic materials is that they must possess noncentrosymmetric (roughly uniaxial) order of chromophores in the bulk material. Thermodynamic relaxation of this chromophore alignment is prevented by raising the glass- transition temperature of the polymeric materials during the electric-field poling process. This is accomplished by (1) thermal imidization of a poly(amic acid) prepolymer, (2) thermally induced chemical crosslinking of an acrylate-type prepolymer, prepared from chromophores containing differing reactive functionalities, (3) sol-gel processing of alkoxysilane- incorporated chromophores, and (4) thermosetting polyurethane/polyurea materials. Analogs of these chromophores that contain reversible photoactive moieties are attached to the surface of functionalized polystyrene and polyacrolein beads permitting the realization of room temperature persistent spectral hole burning exploiting morphology-dependent resonances. Such resonances provide the basis of wavelength coding for the development of three and four-dimensional high-density optical memories.

A thermally stable crosslinked polymer network with large electrooptic coefficient

Organic second-order nonlinear optical materials have been intensely pursued for the past two decades. Remarkable progress has been made in the design and synthesis of chromophores with exceptionally high-/spl mu//spl beta/ values. The superior nonlinearity, along with the inherent ultrafast response and large laser damage threshold, suggests that organic NLO materials are ideal for electro-optic and telecommunication applications. Here, we wish to report our preliminary progress in developing a crosslinked (XL) polymeric material containing a high-/spl mu//spl beta/ chromophore DHPT. At present, the largest electro-optic coefficient obtained from the polymer (20% loading by weight) is 27.5 pm/V (at 1.06 /spl mu/m).

Characterizing and circumventing intermolecular electrostatic interactions in highly electro-optic polymers

In general, polymers possessing non-resonant electro-optic activities exceeding 20 pm/V require chromophores with strong electron withdrawing groups (cyanovinyls, carbon acid moieties, etc.) as well as highly polarizable bridges. Although much progress has been made on designing and preparing materials with molecular electro-optic activities, their incorporation into polymers to show comparable large bulk electro-optic activities has been met with little success. The authors report here the nature of the difficulty of the translation of microscopic to macroscopic electro-optic activity. The optimization of molecular activity increases intermolecular electrostatic interactions between chromophores, and these interactions impede induction of polar ascentric order in the polymers. Theoretical analysis of the problem is presented, as well as one example of a material that is designed to circumvent these interactions. The resulting material possesses electro-optic coefficients as high as 29 pm/V and optical losses as low as 1.5 dB/cm.