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We present an in-depth analysis of the transient response of a resonator fiber optic gyro based on triangular wave phase modulation. Unusual effects have been observed in the process of tracking the resonant frequency of an optical fiber ring resonator (OFRR). There is a distortion phenomenon, unlike the ideally square wave or a pure DC output of the OFRR, but signal overshoot or undershoot occurs. A deep analysis of the influence of the nonideal square wave or pure DC output on gyro performance is fully developed for the first time, to the best of our knowledge. Further analysis shows that this is the transient response process after modulation by the triangular wave, and the process is related both to the parameters of the OFRR and the modulation frequency of the triangular wave. By sampling the steady-state signal of the distortion square wave, or by oversampling the distortion signal to get a number of data, and then accumulating and averaging these data to be demodulated, the distortion's effect can be considerably decreased. OCIS codes: 060.2370, 060.2800.

A method to realize room-temperature operation of a multifrequency Er-doped fiber laser with low-frequency shift feedback placed within a linear laser cavity is theoretically proposed and experimentally demonstrated. Simultaneous multiwavelength lasing with 0.5 nm wavelength spacing is experimentally demonstrated by applying a sinusoidal signal of 10 kHz to a fiber phase modulator inserted within the linear cavity to prevent single wavelength steady-state oscillation. In the linear cavity, an all-polarization-maintaining fiber Sagnac loop is used as a periodic filter, and a single-mode fiber loop with a polarization controller is used as a partial reflector and also as an output port. OCIS codes: 060.0060, 060.2410, 060.2320, 060.5060.

A resonator fiber-optic gyro (R-FOG) is a high-accuracy inertial rotation sensor based on the Sagnac effect. A fiber ring resonator is the core sensing element in the R-FOG. When the frequency of the fiber ring resonator input laser is swept linearly with time, ringing of the output resonance curve is observed. The output field of the fiber ring resonator is derived from the superposition of the light transmitted through the directional coupler directly and the multiple light components circulated in the fiber ring resonator when the frequency of the laser is swept. The amplitude and phase of the output field are analyzed, and it is found that the difference in time for different light components in the fiber ring resonator to reach a point of destructive interference causes the ringing phenomenon. Finally the ringing phenomenon is observed in experiments, and the experimental results agree with the theoretical analysis well. OCIS codes: 060.2370, 060.2800.

The crystallization of amorphous silicon by metal-induced crystallization and metal-induced lateral crystallization was undertaken.

The impact of extended heat treatment on the metal induced lateral crystallization (MILC) rate of amorphous silicon (a-Si) is studied using transmission electron microscopy and orientation image microscopy. Results show that extended heat treatment reduces the MILC rate possibly due to the constantly changing state of the a-Si and decreasing Ni from the Ni covered area. MILC length also increased with the radii of the Ni disc patterns with the longest MILC lengths generated by straight-edged Ni patterns due to their infinite radii of curvature.

Almost all existing studies on inter-satellite radio-frequency (RF) measurement have focused on two-satellite formations. Although some frequency division multiple access and code division multiple access multisatellite RF measurement schemes have been proposed, their poor scalability does not satisfy the inter-satellite measurement requirements of multisatellite formations, especially large-scale formations. Two-way ranging (TWR), which is based on a time division mechanism, is an effective solution that has been used for inter-satellite links in the global positioning system and Beidou navigation constellations. However, the high measurement accuracy achieved with TWR in these navigation constellations is heavily reliant on high-performance atomic clocks and the assistance of navigation ephemeris, which are not available on microsatellite platforms. This work focuses on a scalable multisatellite measurement scheme that adopts a distributed broadcast-based time division multiple access mechanism as the media access control layer and uses an asymmetric double-side TWR method as the physical layer. The measurement performance of the proposed scheme is evaluated through in-depth theoretical modeling, simulation verification, and experimental validation, along with a comprehensive comparison with the conventional TWR method. The experimental results show that centimeter-level measurement accuracy can be achieved with the proposed scheme when only a common miniaturized frequency source is used. This accuracy level is two orders of magnitude better than that of the TWR method, and thus satisfies the application requirements of general large-scale microsatellite formations. [ABSTRACT FROM AUTHOR]

Nickel induced crystallization of amorphous silicon (a-Si) was investigated by selective deposition of Ni on a-Si thin films. The a-Si below and adjacent to the Ni-covered regions were observed to be crystallized after heat treatment at 500 deg C from 1 to 90 hrs. A substantial amount of Ni remained in the region under the original Ni coverage. The crystallized film below the Ni coverage was made up of randomly oriented fine grains while those outside the Ni coverage mainly consisted of large (110)-oriented grains.

Research using Hall effect mobility analysis shows that extended low-temperature isothermal annealing of polycrystalline si(sub 1-x) Ge(sub x) thin film with dopants boron and phosphorus implantation reduces film activation and conductivity. Grain boundary segregation of dopant during extend annealing may cause the reduced effects. Oxidation of Si(sub 1-x) Ge(sub x) doped with phosphorus occurs at 600 degrees centigrade.

We propose a MEMS gyroscope system working with a fixed resonance frequency which combines resonant constant-frequency (RCF) driving and real-time automatic mode-matching technique with the help of linear tuning triangular capacitors. The special tuning capacitors are implemented in both the gyroscope drive mode and sense mode as drive-mode frequency-tuning (DFT) and sense-mode frequency-tuning (SFT), respectively. RCF assures that the drive-mode equivalent resonance frequency after tuned can keep with the given constant excitation frequency, while real-time automatic mode-matching further eliminates mismatches between the drive-mode and sense-mode equivalent resonance frequencies. As a result, the gyroscope system achieves constancy and equality of the excitation frequency and two modal resonance frequencies. Performance evaluations show that the gyroscope with the sense mode quality factor of 26.7k reaches bias instability of 0.09°/h and angle random walk of 0.0087°/ $\surd \text{h}$ under room temperature without any compensation, and is capable of detecting an angular rate as low as 0.001°/s. [ABSTRACT FROM AUTHOR]