Piezoelectric Fiber Coatings and Micro-Tubes
- PDF / 1,749,915 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 1 Downloads / 211 Views
ABSTRACT Axially symmetric coatings of ZnO and PZT have been deposited onto fiber substrates by reactive dc magnetron sputtering. Multi-layer Cr/Au/ZnO/Cr/Au coating structures on optical fibers have been used to make integrated phase modulator devices. An analysis of the structural properties and piezoelectric response of the phase modulator devices will be presented. Microtubes of ZnO and Pt/ZnO/Pt multi-layers have been prepared by coating polyester fibers that act as a fugitive phase. After burning away the polyester fiber, up to 3 cm long micro-tubes with a 23 jim inside diameter and 3 to 9 jim wall thickness were obtained. INTRODUCTION Piezoelectric coatings on optical fibers are currently under study for the fabrication of integrated piezoelectric fiber optic phase modulator (PFOM) devices.1 ,2,3 A typical phase modulator structure consists of axially symmetric bottom electrode, piezoelectric, and top electrode layers, and the length of the top electrode defines the length of the modulator.4 ,5 When an electric field is applied across the piezoelectric layer, the inverse piezoelectric effect of the coating introduces a strain in the underlying fiber substrate. Due to the elasto-optic effect, a refractive index change occurs in the strained length of fiber. For a light signal passing through the optical fiber, the combination of path length change and refractive index change causes a phase shift that is dependent upon the electric field applied to the piezoelectric layer. 2 ,6 This paper presents results on the fabrication and analysis of ZnO-based PFOM devices and shows initial results on multi-magnetron sputter deposition of PZT coatings on optical fibers.
The equipment developed for deposition of coatings on optical fibers has also been used for making ZnO micro-tubes. ZnO is sputter deposited onto polyester fibers and a subsequent annealing process burns away the polyester fiber fugitive phase. 7 The technique could be used to make micro-tubes of a broad range of materials. This paper demonstrates the capability of making multi-layer micro-tube structures. EXPERIMENTAL PROCEDURE PFOM devices based on ZnO were prepared by using a combination of thermal evaporation and reactive dc magnetron sputtering techniques. Telecommunication optical fibers (125 4im diameter, 9 4tm core diameter) were stripped and cleaned in dichloromethane and isopropanol in an ultrasonic bath. After chemical cleaning, the fibers were thermally treated at 400'C for 20 min to remove organic residues and enhance adhesion of the Cr/Au coating. The cleaned fibers were mounted in a fiber rotation sample holder that was mounted horizontally in an evaporation chamber where 13 nm thick Cr and 130 nm thick Au coatings were deposited at rates of 1 and 10 nm/min, respectively, using a fiber rotation speed of 2 rpm. Following the deposition of the Cr/Au bottom electrode layers, a 5 - 6 jim thick ZnO coating was deposited by sputtering from a 10 cm diameter Zn target using a mixed Ar and 02 atmosphere with a total pressure (P) of 1.50 Pa, oxygen
Data Loading...
