A dense ceramic with an ordered perovskite structure with chemical formula Ba(Mg1/3Ta2/3)O3 is prepared, aiming at materials for a dielectric resonator with temperature-stable high dielectric contsant and low loss at microwave frequency. A small amount of Mn ion is doped to the sample to complete the sintering. The dielectric constant and unloaded Q are 25 and 16800 at 10.5 GHz respectively. The temperature coefficient of resonant frequency is estimated as 2.7 ppm/°C in the vicinity of room temperature. The value of Q we obtained is the highest among those reported so far on ceramics having a similar characteristic.

Solid solution ceramics in the Ba(Zn1/3Nb2/3)O3(BZN)–Sr(Zn1/3Nb2/3)O3 (SZN) system have been studied with a view to finding materials for use as dielectric resonators at microwave frequency. The relative dielectric constant and the unloaded Q at 10 GHz are respectively 41 and 5400 for BZN, and 40 and 2000 for SZN. The temperature coefficient of the resonant frequency is estimated as 30 ppm/°C for BZN and -38 ppm/°C for SZN. The dielectric constant of 0.3 BZN–0.7 SZN ceramic is nearly independent of temperature, which gives a very small estimated temperature coefficient of the resonant frequency of -5 ppm/°C.

The lasing frequencies of a Brillouin fiber ring laser are shifted slightly from the resonant frequencies of the cold fiber ring resonator due to the optical Kerr effect and the nonlinear phase shift associated with s t i m u l w Brillouin scattering (SBS) used as the gain mechanism in this type of laser. These frequency pulling effects are investigated in detail both theoretically and experimentally. The results of this study are useful in many Brillouin fiber ring laser applications such as Brillouin fiber optic gyroscopes, microwave generators, and frequency shifters. To the authors' knowledge this is the fiqt time the frequency pulling effect caused by the nonlinear phase shift associated with SBS is reported.

We have demonstrated a Brillouin fiber-optic gyro that utilizes push-pull phase modulation in the ring cavity to suppress frequency locking. This in-line modulation allows an all-fiber system with optical reciprocity. A tenfold reduction of the width of the lock-in range is observed experimentally.

A novel demodulation scheme for interferometers with optical phase modulation is described. The optical phase shift is measured by mixing a train of square digital pulses with a photodetector current and adjusting the pulse spacing by using an electronic closed loop. The optical phase shift is tracked with deviation less than 0.007 rad, which can be easily corrected by using a look-up table. An experimental optically open-loop fiberoptic gyroscope that uses this demodulation shows a linear scale factor in good agreement with theory.In the interferometric fiber-optic gyroscope with optical phase modulation, the detector current is given by' ID(t) = 21 + Cos[nm Cos(w0mt) + OR]},( 1) where Io is the maximum detector current, Am is the amplitude of differential phase modulation, air = 27rfm is the modulation frequency, and OR is the rotation-induced Sagnac phase shift. In practical gyroscope systems, a wide dynamic range with good linearity is desirable. For this purpose many demodulation systems have been proposed. 2` These can be classified into two categories: closed-loop and open-loop systems.