Fabrication and structural analysis of ZnO coated fiber optic phase modulators

Abstract

Fiber optic modulators were fabricated by coating optical fibers with electrode and piezoelectric ZnO layers. The techniques of piezoelectric fiber optic modulator (PFOM) fabrication are presented, and the microstructure and crystallographic texture of the coatings are analyzed. In order to produce thick (approximately 5 mm) ZnO coatings, it was necessary to study the reactive dc magnetron sputtering process in O 2 ͞Ar gas mixtures under conditions close to the transition between an oxidized and nonoxidized Zn target surface. In situ quartz crystal microbalance measurements of the deposition rate revealed thee distinct regions in the deposition rate (R) vs oxygen partial pressure (P O2 ) behavior, at constant total pressure, for sputtering under conditions that provided an oxidized Zn target surface. Additionally, a transition between oxygen and argon dominated sputtering as observed by varying the sputtering pressure while maintaining a constant P O 2 . The transition between oxygen and argon dominated sputtering influences R to varying extents within the three R vs P O 2 regions for an oxidized target surface. Correlations among the cathode current and voltage, deposition rate, and gas flow rate are presented to give a better understanding of the reactive sputtering processes occurring at the oxidized Zn target surface. Sputtering conditions optimized for a high ZnO deposition rate were used to produce ͗001͘ radially oriented ZnO fiber coatings for PFOM devices that can produce optical phase shifts as large as 0.38 rad͞V.

Planar defects in ZnO thin films deposited on optical fibers and flat substrates

“…Details on the deposition process have been previously reported. 38 X-ray diffraction was used to analyze the crystalline phase formation and preferred orientation of the ZnO thin films. A 114.6 nm diameter Debye-Scherrer camera was used to analyze the thin film fiber coatings since this technique is ideal for analysis of fiber samples and can provide information about radial textures.…”

“…For fiber samples analyzed with a Debye-Scherrer camera, the [0001] radial preferred orientation could be determined from the high relative intensity of the 000l reflections and the change of the 000l reflections from continuous rings to short arcs on the exposed film. 38 By comparing the thin film 0002 peak width at half maximum intensity with a ZnO powder pattern, it is apparent that the ZnO coatings on both flat and fiber substrates exhibit significant broadening as shown in Figs. 2 and 3, respectively.…”

Real‐time device tracking under MRI using an acousto‐optic active marker

“…Use of a thin piezoelectric film will eliminate the need for the bulky PCB interface and reduce the size of the acousto-optic modulator. Thin piezoelectric film will only add a few µm of thickness to the optical fiber 57,58 enabling the acousto-optic modulator profiles as small as to size of the optical fiber; i.e., 125 µm with standard optical fibers and 80 µm with thin optical fibers. However, the fragile thin film still has to be protected by an additional protective layer that will slightly increase the overall diameter.…”

3D mask modules using two-photon direct laser writingtechnology for continuous lithography process on fibers

“…In order to realize more functionality and applications, it is necessary to directly integrate electronic, computational and other functionality into textile fibers. Therefore, there are strong academic and industry interests in developing high resolution micromachining technology on fiber substrates [1][2][3][4]. As a matter of facts, practical applications cannot be expected unless the aforementioned micromachining technology can be utilized for mass production because the fiber substrates are not compatible with batch processes.…”