Nickel ͑Ni͒ induced crystallization of amorphous silicon (a-Si) has been studied by selective deposition of Ni on a-Si thin films. The a-Si under and near the Ni-covered regions was found to be crystallized after heat treatment at 500°C from 1 to 90 h. Micro-Auger electron spectroscopy revealed that a large amount of Ni stayed in the region under the original Ni coverage, but no Ni was detected either in the crystallized region next to the Ni coverage or in the amorphous region beyond the front of the laterally crystallized Si. X-ray photoelectron spectroscopy revealed a nonuniform Ni distribution through the depth of the crystallized film under the original Ni coverage. In particular, a Ni concentration peak was found to exist at the interface of the crystallized Si and the buried oxide. It was found that a layer of 5-nm-thick Ni could effectively induce lateral crystallization of over 100 m of a-Si, but the lateral crystallization rate was found to decrease upon extended heat treatment. Transmission electron microscopy analysis showed that the crystallized film under the Ni coverage was composed of randomly oriented fine grains, while that outside the Ni coverage was mainly composed of large ͑110͒-oriented grains. A unified mechanism is proposed to explain the Ni induced crystallization of a-Si and possible reasons for the reduction in the lateral crystallization rate are discussed.

Resonator micro optic gyro (RMOG) is a promising candidate for applications requiring small, light and robust gyros. In optical passive ring resonator gyros, clockwise and counter clockwise lightwaves are modulated at different frequencies to reduce the backscattering induced noise. The effectiveness of this technique, however, is determined by the carrier suppression level. Accurate modulation index and high environmental temperature stability is required for achieving high total carrier suppression for the traditional single phase modulation technique (SPMT). In this paper, we propose an RMOG based on the double phase modulation technique (DPMT). Compared with the traditional SPMT, two additional phase modulations are added to provide additional carrier suppression. It is found that the control accuracy of the modulation index and temperature stability is relaxed more than 30 times. It is easily performed for reducing the backscattering error below the shot noise limited sensitivity. The modulation parameters in the DPMT are analyzed and optimized. Based on the optimum parameters of the DPMT, a bias stability of 1.85×10⁻⁴ rad/s is successfully demonstrated in the polarization maintaining silica waveguide resonator with the length of 7.9 cm. This is the best result reported to date, to the best of our knowledge, for a waveguide type passive ring resonator gyro.

Compared to conventional solid phase crystallized (SPC) thin-film transistors (TFT's), metal induced laterally crystallized (MILC) TFT's exhibit significantly enhanced performance at reduced processing temperature. It is concluded that the major improvements in MILC-TFT's result from the growth of the crystal grains in a direction longitudinal to that of the current flow, whereas in SPC-TFT's, the grain boundaries are randomly oriented. It is also observed in this work that while the MILC-TFT's are less sensitive to short-channel effects (SCE's), their leakage current exhibits higher sensitivity to channel length reduction. These differences again can be traced to the different arrangements of the grain boundaries in the two types of devices.

A resonant fiber optic gyroscope (RFOG) based on the reciprocal phase modulation-demodulation technique is proposed and demonstrated. The residual amplitude modulation induced error of the phase modulator, and the effect of laser frequency noise are all suppressed thanks to the reciprocity of the proposed signal processing scheme. Compared with the past separate modulation-demodulation RFOG, the angular random walk is improved by a factor of 15 times from 0.08°/√h to 0.0052°/√h, and the bias stability is improved from 0.3°/h to 0.06°/h.

A detection system in the resonator fiber-optic gyro is set up by the phase modulation (PM) spectroscopy technique. The slope of the demodulated curve near the resonant point is found to affect the ultimate sensitivity of the gyro. To maximize the demodulated signal slope, the modulation frequency and index are optimized by the expansion of the Bessel function and optical field overlapping method. Using different PM frequencies for the light waves, the open-loop gyro output signal is observed. The modulation frequency in this PM technique is limited only by the cutoff frequency of the LiNbO3 phase modulators, which can reach several gigahertz. This detection technique and system can be applied to the resonator micro-optic gyro with a less than 10 cm long integrated optical ring.

Abstract-Process and material characterization of the crystallization of amorphous silicon by metal-induced crystallization (MIC) and metal-induced lateral crystallization (MILC) using evaporated Ni has been performed. An activation energy of about 2 eV has been obtained for the MILC rate. The Ni content in the MILC area is about 0.02 atomic %, significantly higher than the solid solubility limit of Ni in crystalline Si at the crystallization temperature of 500 C. A prominent Ni peak has been detected at the MILC front using scanning secondary ion mass spectrometry. The MIC/MILC interface has been determined to be highly defective, comprising a continuous grain boundary with high Ni concentration. The effects of the relative locations of this interface and the metallurgical junctions on TFT performance have been studied.Index Terms-Grain boundary, MILC, nickel, thin-film transistor.

Resonator fiber optic gyro (RFOG) based on the Sagnac effect has the potential to achieve the inertial navigation system requirement with a short sensing coil. Semiconductor laser is one of the key elements for integration and miniaturization of the RFOG. In this paper, an RFOG employing a semiconductor laser is demonstrated. The model of the laser frequency noise induced error in the RFOG is described. To attenuate the laser frequency noise induced error, active frequency stabilization is applied. An online laser frequency noise observation is built, as a powerful optimum criterion for the loop parameters. Moreover, the laser frequency noise observation method is developed as a new measurement tool. With a fast digital proportional integrator based on a single field programmable gate array applied in the active stabilization loop, the laser frequency noise is reduced to 0.021 Hz (1σ). It is equivalent to a rotation rate of 0.07°/h, and close to the shot noise limit for the RFOG. As a result, a bias stability of open-loop gyro output is 9.5°/h (1σ) for the integration time 10 s in an hour observed in the RFOG. To the best of our knowledge, this result is the best long-term stability using the miniature semiconductor laser.

Abstract. We report the first demonstration of silica waveguide optical passive ring resonator gyro ͑OPRG͒ based on the phase modulation spectroscopy technique. The ring resonator is composed of a 6-cm-long silica waveguide. Observed from the resonance curve, the free spectral range ͑FSR͒ of the resonator, the full width at half maximum ͑FWHM͒ of the resonance curve, the finesse ͑F͒ of the resonator, and the resonance depth are 3.4 GHz, 62 MHz, 54.8, and 70%, respectively. The detection sensitivity of this OPRG will be 7.3ϫ 10 −5 rad/ s. In the experiments, there is an acoustic-optical modulator ͑AOM͒ in each light loop. We lock the lasing frequency at the resonance frequency of the silica waveguide ring resonator for counterclockwise ͑CCW͒ lightwave; the frequency difference between the driving frequencies of the two AOMs is equivalent to the Sagnac frequency difference caused by gyro rotation. Thus, the gyro output is observed. A small, robust, tactical-grade performance gyro is vital for the successful implementation of the smart weapons and surveillance apparatus. A waveguide-type optical passive ring resonator gyro ͑OPRG͒ is a promising candidate. 1,2The OPRG is a frequency-sensitive device. The gyro rotation is determined by the resonance frequency difference in the clockwise ͑CW͒ and counterclockwise ͑CCW͒ lightwaves due to the Sagnac effect.1 Light circulating many turns in the ring resonator can build up the Sagnac effect. Thus, a short-length sensing loop is required. In this letter, the phase modulation ͑PM͒ spectroscopy technique is chosen to detect the gyro signal using LiNbO 3 phase modulators.3 In the PM spectroscopy technique, the modulating signal and feedback signal do not interact, moreover the LiNbO 3 phase modulators are easy to be integrated with other optical devices. They will make the OPRG compact. Figure 1 shows a schematic diagram of the experimental setup of the OPRG system. The resonator is composed of a 6-cm-long silica waveguide ring and a directional coupler ͑C4͒. The wavelength of the laser is 1550 nm and the diameter of the resonator is 1.9 cm, so the scale-factor of the OPRG is 1 0.84ϫ 10 4 Hz/ rad s −1 .The silica planar lightwave circuit ͑PLC͒ is the key rotating sensing element in the OPRG. It consists of two input/output directional couplers ͑C2 and C3͒ and one resonator coupler ͑C4͒. The coupling ratio of couplers C2 and C3 is designed as 50%. The coupling ratio of coupler C4 is optimized by the total loss in the ring resonator, including propagation loss of silica waveguide ring, excess loss due to the curvature, and excess loss through coupler C4. Considering the temporal coherence of the laser, the resonance curve of a ring resonator is given by 4,5where is the resonance depth; ␦ is the phase shift around one trip of the ring;1/2 ͓exp͑−⌬f͔͒; ␣ R is the total propagation loss in the ring; k C and ␣ C are the coupling ratio and coupling loss of resonator coupler C4, respectively; ⌬f is the spectral linewidth of the laser; and is the optical transmission time in the ring a...