Claude Muller

Efficient miniature fiber-optic tunable filter based on intracore Bragg grating and electrically resistive coating

An electrically tunable reflection filter based on a platinum-coated single-mode optical fiber that contains an intracore Bragg grating has been demonstrated. The device shows a dc tuning range of 2.15 nm with a corresponding electrical power of 0.54 W. Wavelength modulation (WM) has been observed at frequencies lower than 100 Hz. The wavelength shift depends linearly on the electrical input power. A maximum efficiency of 4.1 nm/W is obtained for dc tuning.

Tunable loss filter based on metal-coated long-period fiber grating

An all-fiber electrically tunable loss filter that is based on photoinduced long-period grating coated by Ti-Pt metal coating was developed and investigated. Maximum wavelength tuning of 11 nm with an applied power of 0.67 W was achieved for the HE17 cladding mode resonance peak.

Integration of high-Q BAW resonators and filters above IC

A double-lattice BAW filter with balanced input and output is designed with a center frequency of 2.14GHz. The filter is integrated directly above a 0.25/spl mu/m BiCMOS RF IC. Insertion loss of -3dB and out-of-band rejection better than -50dB are achieved. An integrated LNA comprising two broadband amplifiers and one BAW filter is also presented.

A Low-Power 2.4GHz CMOS Receiver Front-End Using BAW Resonators

A low-power 2.4GHz heterodyne receiver front-end is integrated in 0.18mu;m CMOS using BAW solidly mounted resonators. The resonators with Qs of up to 580, provide both impedance matching and selectivity. An image rejection of up to 50dB, a NF of 11dB and IIP3 of -16.1dBm with a power dissipation of 1.8mW are demonstrated

All-fibre acousto-optic modulator using ZnO piezoelectric actuators

Abstract Acousto-optic modulators on optical fibres have been realized using a coating of zinc oxide. The phase shift response of the modulators is 0.5 mrad V −1 from 10 kHz up to 10 MHz and as high as 0.3 rad V −1 on radial resonance modes of the fibre above 20 MHz. A phase-shift amplitude of π /2 has been realized with 60 mW of driving power.

A 2.4GHz MEMS-Based Transceiver

Miniaturization and reduction of power dissipation are two issues that currently prevent the seamless integration of wireless and networking capability into any tiny high-tech object such as hearing aids or miniature drug delivery monitoring devices or implants. The combination of MEMS technologies, yielding novel devices such as RF bulk acoustic wave (BAW) resonators and filters or low frequency silicon resonators, with RF ICs call for several innovations at the architectural, packaging, circuit and device levels to demonstrate the miniaturization and power reduction potential of the involved technologies.

Piezoelectric coatings for active optical fiber devices

A new class of active fiber devices based on piezoelectric coated optical fibers is currently being developed. The piezoelectric coating is used to produce acoustic waves within the optical fiber and these acoustic waves interfere with optical signals passing through the fiber waveguide. Optical phase modulation devices based on piezoelectric coated fibers have been demonstrated and the behavior of these devices will be reviewed. A second type of active optical fiber device has been fabricated by integrating a piezoelectric fiber coating with an intra-core Bragg grating, which acts as a reflection filter. The primary interest of this work is to produce a piezoelectric fiber optic tunable filter. These types of active all-fiber devices show promise for a variety of applications including telecommunications and sensing networks. The performance of active optical fiber devices that use piezoelectric coatings is dependent on the device structure and the piezoelectric properties of the fiber coating. Several important geometric parameters (e.g. coating thickness and device length) that influence device performance have been experimentally identified. Additionally, several relationships between the fiber coating sputter deposition process, microstructure, and properties have been observed for piezoelectric ZnO fiber coatings. Recent advances in the development of active all-fiber devices are presented.

Microstructure and defects of wurtzite structure thin films

ZnO and AlN, which exhibit the wurtzite structure, were deposited onto metal coated SiO2 substrates by sputtering. X-ray diffraction (XRD) indicated that the films contained no second phases and exhibited an [0001] texture. Transmission electron microscopy (TEM) observations confirmed the XRD results and revealed the columnar microstructure of the films. The width of the columnar grains were less than 30 nm for AIN and between 100 and 400 nm for ZnO. In the ZnO grains, a large concentration of defects were identified, which included dislocations and stacking faults that lie on the basal plane

Optical fibers with patterned ZnO/electrode coatings for flexural actuators

A fiber-based flexural actuator was developed using a patterned piezoelectric ZnO/electrode fiber coating on a standard telecommunications optical fiber. The actuator was composed of a concentric inner Cr/Au electrode, a thick sputtered ZnO coating, and an outer Cr/Au electrode. Using standard photolithography, 30-μm wide gaps in one of the electrodes were patterned along 2-cm lengths parallel with the fiber axis. This device can be driven in a bimorph mode. It was demonstrated that a split electrode actuator could be excited into electromechanical resonance to produce useful displacements at the end of the fiber. Such flexural fiber actuators could be used in scanning near field optical microscopes for fiber tip height adjustment. In addition, the actuator design can be extended to manufacture two-axis integrated fiber alignment devices.

All-fiber phase-modulated master oscillator power amplifier for coherent communication

An all-fiber phase-modulated master oscillator power amplifier for free-space coherent communication is presented. A distributed-feedback fiber laser at 1.06 /spl mu/m is used as master oscillator. A novel phase modulator based on a ZnO-coated single-mode fiber modulates the single frequency communication signal. The modulated signal is then amplified in a double-clad doped fiber power amplifier. Up to 1 W cw single-frequency output power, phase modulated at 196 MHz, has been obtained.