Dai Enguang

Surface-related phase noise in SAW resonators

With the advent of nanotechnologies, electronic devices are shrinking in thickness and width to reduce mass and, thereby, increase frequency and spe Lithographic approaches are capable of creating metal connections with thickness and lateral dimensions down to about 20 nm, approaching the molecular scale. As a result, the dimensions of outer particles are comparable with, or even larger than, those of active or passive regions in electronics devices. Therefore, directing our attention toward the effect of surface fluctuations is of practical significance. In fact, electronic device surface-related phenomena have already received more and more attention as device size decreases. In connection with surface phase noise, selection of a suitable device with high surface sensitivity is important. In this paper, high Q-value surface acoustic wave resonators were employed because of their strong sensitivity to surface perturbation. Phase noise in SAW resonators related to surface particle motion has been examined both theoretically and experimentally. This kind of noise has been studied from the point of view of a stochastic process resulting from particle molecular adsorption and desorption. Experimental results suggest that some volatile vapors can change flicker noise 1/f and random walk noise 1/f2. An analysis has been made indicating that these effects are not associated with Q value variation, but are generated by the change in the dynamic rate of adsorption and desorption of surface particles. Research on particle motion above the device substrate might explain the differences observed from the model based only on the substrate itself. Results might lead to a better understanding of the phase noise mechanism in micro-electronic devices and help us to build oscillators with improved performance.

High speed integrated acousto-optic switch with high extinction ratio

The technology of single phase unidirectional transducer and focused transducer was adopted for the design of acousto-optic switch. The extinction ratio up to 32 dB and switching speed at 300 ns was achieved.

State-of-the-art instruments based upon SAW wireless tags, SAW match filters, and SAW resonators

A theoretical analysis for the SAW wireless tag for wireless instrumentation was proposed. Employing the developed wireless tag, a telemetry instrument was also developed. Other SAW device based systems such as SAW match filter based optical time-domain reflectometer and high Q-value SAW resonator based analytical instruments are also reported. These state-of-the-art instruments can enlarge the application scope of SAW technology.

Fiber-optic feeding in hybrid wideband CDMA/FDMA/WDM microcellular system

A new fiber-based microcellular system was proposed. The developed hybrid CDMA/FDMA/WDM system is highly spectrally efficient and each channel is more robust against interferences from other optical channels. Some experimental results which show promise in practical deployment are presented. In the experimental system, some self-designed key devices were used.

A novel WDM-CDMA optical fiber communication system with asynchronous despreading technology

A WDM/CDMA optical fiber communication system with asynchronous despreading technology employing surface acoustic wave MSK match filter is reported. Key devices were designed and fabricated. The system can be used as a signaling network to manage other networks and can be evolved into a multi-stage multiplexing system.

Micro-devices based on spectrum shape deformation

Traditionally, resonate device related sensors are mainly for the detection of resonate peak shift resulting from outer environment disturbance. Besides, there are other types of sensors based upon the peak position detection as well. Electrical frequency spectrum shape or optical spectrum shape deformation are seldom employed as measurand. A new point of view on sensors will be demonstrated both in electrical domain and in optical domain. Different from the detection of the resonate peak, spectrum shape monitoring can provide us with different information.

Application of spread spectrum technology at 64Mcps and 2Mbps as OAM signals in transparent optical networks

The application of wideband spread spectrum signal at standard 2.048Mbitls and 64Mchiph on the optical carrier for the transmission of operation, administration and maintenance signals has been developed and evaluated.

Theory and implementation of wireless transponders

A theoretical analysis for the surface-acoustic-wave-based wireless transponder in a wireless system has been proposed in this paper. Radio transponders were also implemented based upon the theory of coupling of modes. The proposed theory can be employed in the simulation of amplitude- and phase-coded devices with different segments,.

New researches on low noise signal generation based upon electronic devices with strong surface sensitivity

The surface molecular motion phase noise existed in electronic components with strong surface sensitivity has been extensively analyzed both from theory and experiments. To select a suitable device with remarkable surface sensitivity is very important for the efficiently research. In this paper, two-port and high Q-value SAW resonators were adopted. The phase noise has been studied from the point of view of stochastic process resulting from gas molecular adsorption and desorption. Experimental results have shown that some organic vapors can reduce the flicker noise (1/f) and random walk(1/f/sup 2/) noise. Analysis has been made that these effects are not from the e-value increment, but from the changing of dynamic rate of adsorption and desorption. Research on gas motion above the device substrate might explain some phenomenon difficulty explained by the model based only upon substrate itself.

Research on special resonant technologies in photonics system

Oscillators that can directly convert light energy into spectrally pure microwave and millimeter wave signals are very important. Although these approaches offer significant advantages, they do provide several challenges for practical implementation. As far as the hybrid acoustic/electro-optic resonator is concerned, it is easy to obtain oscillation and has good frequency stability. The technology developed here is very suitable for the long distance monitor, long distance oscillation control or remote sensing. Based upon the technology, a series of novel sensors or instrumentation can be developed. Because the technology has combined SAW technology and optical fiber communication technology, both fiber sensor and SAW sensor can be built on the same technology platform. This technology can link with an IF acquisition system. To acquire IF frequency signal coming from a microwave mixer the data acquisition system itself should be stable enough. The developed system can acquire frequency signals from ten signal-channels, the highest acquisition frequency was up to 8.5MHz and the frequency resolution was 0.5Hz.