The development of an all-DNA-based electro-optic waveguide modulator

Marine-based deoxyribonucleic acid (DNA) has been identified as a promising new biopolymer in the field of nonlinear optic materials for electro-optic, optical memory and optical amplifier applications. DNA has demonstrated low optical loss at the communications wavelengths, is an abundant and inexpensive green material, is temperature stable up to 200°C, and has a unique double helical structure that may aid in chromophore alignment for poled polymer applications. The DNA is purified from salmon roe and milt sacs, waste products of the Japanese fishing industry. To be compatible with photonics applications, the water soluble DNA is precipitated with a surfactant complex, cetyltrimethl-ammonium chloride (CTMA), to form a water insoluble complex, DNA-CTMA, for application as a nonlinear optical material. Several novel processes have been developed specifically for using this biopolymer in photonics applications.; In order to fabricate an all-DNA-CTMA waveguide (using DNA-CTMA for both the core and cladding layers), it is necessary to crosslink the DNA-CTMA films. Crosslinking makes the films resistant to their initial solvent; this permits spin-coating of successive DNA-CTMA layers without solvent damage. A chromophore dye is added to the core layer to allow for an electro-optic coefficient to be induced through contact poling. The dye also provides the index of refraction difference between the core and cladding layers to meet waveguiding conditions. Through contact poling, an electro-optic (EO) coefficient comparable to that in other polymers was demonstrated in crosslinked DNA-CTMA films with the chromophore dye Disperse Red 1. This EO effect allows for the creation of an all-DNA EO waveguide modulator.; DNA was successfully developed into a useful polymer material for application in an all-DNA-based EO waveguide modulator. This research demonstrated several firsts with this material: the first example of a poled DNA-based chromophore film was demonstrated, the first three-layer all-DNA-based waveguide was demonstrated, and the first three-layer all-DNA based EO modulating device was demonstrated. Additionally, many unique processing and fabrication techniques were developed specifically for integration of DNA into a photonics device. This research demonstrates that the DNA-based biopolymer can successfully be integrated into photonics applications.