Towards a solid-state ring laser gyroscope

In this paper, we report our recent progress towards a solid-state ring laser gyroscope (RLG), where mode competition is circumvented by active control of differential losses, and nonlinear effects are mitigated by longitudinal vibration of the gain medium. The resulting dynamics is significantly different from that of a classical helium–neon RLG, owing in particular to parametric resonances that occur when the Sagnac frequency is an integer multiple of the crystal vibration frequency. We describe the main experimental and theoretical results obtained so far, and the prospects of practical applications in the near future.     

Proposal of a semiconductor ring laser gyroscope

We proposed a novel optical inertial rotation sensor using a semiconductor ring laser (SRL). The frequency difference between the two counter propagating oscillation frequencies was automatically generated in a mechanically rotated SRL, which consisted of a pig-tailed laser diode amplifier module. And the Sagnac frequency shift could be detected at the first time as a beat note by the terminal voltage change of the SRL without branching the circulating optical power. These experimental results verify that an SRL operates as an optical inertial rotation sensor based on the Sagnac effect.     

激光陀螺中背向散射的研究

为了研究谐振腔形状变化对激光陀螺中背向散射的影响,基于矢量叠加理论,分析了激光陀螺背向散射源及其对总的背向散射的影响.根据背向散射对顺逆时针光的耦合作用,推导出了总的背向散射系数与顺逆时针旋转光光强的关系式.基于这一关系,设计实验,通过施加电压使谐振腔反射镜到不同位置来改变光腔形状变化,同时测量光强交流量的振幅,得到了总的背向散射系数的变化曲线.通过与仿真结果对比,验证了背向散射的矢量叠加理论.     

Study of a carbon dioxide ring laser gyroscope

We have experimentally investigated a basic ring laser gyroscope (RLG) with carbon dioxide gain, and studied the prospects of developing a practical CO₂ RLG. Rotation sensing was demonstrated on a number of transitions in the 9.4 m and 10.4 m vibration-rotation bands. Gyro response is discussed with regard to lock-in, bias, homogeneous broadening effects, and high power operation. We show that such a system may offer important advantages over standard helium-neon RLGs, including reduced quantum limit and backscattering. The prospects and possible approaches for developing a practical high power CO₂ RLG are discussed, and a method of eliminating cross-saturation at high pressure is proposed and analyzed.     

An argon ion ring laser as a gyroscope

As a prototype gyroscope for a precision measurement of the Earth's rotation _E, we set up an argon ion ring laser with an area of 1.4 m². Different cavity geometries were tested in order to achieve a cancellation of the effect of the plasma flow. In a set-up with two laser tubes of the same type facing towards opposite directions, a stability of the beat frequency of 2–3 _E was measured. In a configuration with a double transition of the laser beam through the tube, the lock-in threshold was too high for the Earth's rotation to be measured, however, no effect of the plasma flow was observed.     

Transformation of a soliton at a point of zero nonlinearity

The transformation of a soliton in a zone with a sign-changing nonlinearity has been investigated on the basis of the Korteweg-de Vries equation. It is shown that after passage through the critical zone a soliton with opposite polarity is formed in the wave field and, together with the previously known mechanism of secondary-soliton generation as a result of a pedestal formed at the adiabatic stage, there also exists another mechanism which is associated with the transformation of the wave in a zone of variable nonlinearity after the critical point. It is shown that both mechanisms make approximately the same contribution to the secondary-soliton energetics. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 1, 113–117 (10 January 1997)     

Determination of the losses in a ruby laser with a misaligned resonator

A technique for the determination of the losses in a ruby laser with a misaligned resonator is presented. It is shown that a probabilistic formula for the power generation correctly describes the relation between the generated power and the angle between the resonator mirrors if the experimentally determined loss figures are inserted into this formula.     

Frequency shift in a fiber laser resonator

A new model that describes the influence of a laser intracavity frequency shifter is proposed. Laser line broadening that is due to the presence of the frequency shift is derived. The theoretical model is validated by experimental results. Multiwavelength operation of this laser is explained.     

Frequency shift in a mode-selected dye laser

It is found that a flash-lamp pumped dye laser with two tilted Fabry-Pérot interferometer wavelength selectors shows frequency shift, both with dielectric or resonant reflector mirrors. The shift can be towards red or blue, even within one pulse, limited by the passband of the system. The “wavelength-time effect” and inhomogeneous pumping are indicated as possible mechanisms.     

如何解决光电灵敏电流计的零点漂移

大家知道，在磁场中的运动电荷不管受不受其它外力作用，洛仑兹力总是不做功．因为洛仑兹力总是跟速度方向垂直，它只改变速度方向，不改变速度大小．但在有些实际问题中，经常需要将洛仑兹力巧妙地进行分解，运用在某个方向上做功或者与其它外力在某个方向上叠加产生加速度来分析处理问题，现举例说明。     

Effect of nonsinusoidal phase modulation on the zero shift in a fiber ring interferometer

Institute of Applied Physics, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, No. 10, pp. 1345–1349, October, 1994.     

On the zero temperature critical point in heavy fermions

We generalize the scaling theory of heavy fermions for the case the shift exponent describing the critical Néel line is different from the crossover exponent characterizing the coherence line. We obtain the properties of the non-Fermi liquid system at the critical point and in particular the electrical resistivity. We study violation of hyperscaling in the Fermi liquid regime below the coherence line where the properties of heavy fermion systems are described by mean-field exponents.     

扩束棱镜在激光陀螺信号检测中的应用

本文指出,利用扩束棱镜将高斯光斑在一维方向扩束,能明显地提高多个探测器所探测的激光陀螺拍频信号的信噪比.     

光纤激光陀螺系统的优化设计

分析研究了光纤激光陀螺系统的工作原理和基本构成,根据系统中各器件的性能指标对光纤激光陀螺的基本结构、性能参数进行了计算机模拟优化设计。采用双向激射双向输出结构保证光路的互易性。利用光纤环形器、掺铒光纤和光纤Bragg光栅实现滤模、选模和压缩线宽功能。针对其输出信号特点,提出利用偏振分束的方式判断陀螺工作转动方向,并最终计算陀螺转动角速度的信号处理方案。     

Nonreciprocity of counterpropagating signals in a monolithically integrated Sagnac interferometer

We demonstrate nonlinearly induced nonreciprocity of counterpropagating waves in a monolithically integrated Sagnac interferometer that employs a semiconductor optical amplifier as the nonlinear element. We show that the dependence of the linewidth enhancement factor on charge injection can influence the third-order nonlinearity in the semiconductor gain medium to a surprisingly large degree. This effect is utilized to control the phases of the counterpropagating signals in the interferometer. A theoretical model is used to explain the experimental observations. We show that these effects have significant practical implications by demonstrating an all-optical controlled-NOT gate.     

Suppressing the mechanical quadrature error of a quartz double-H gyroscope through laser trimming

In this paper,we introduce a z-axis quartz gyroscope using a double-H tuning fork,which has a high sensitivity.However,it also causes a large mechanical quadrature error.The laser trimming method is used to suppress this error at quartz level.The trimming law is obtained through the finite element method(FEM).A femtosecond laser processing system is used to trim the gold balancing masses on the beams,and experimental results are basically consistent with the simulated ones.The mechanical quadrature error is suppressed by 96%,from 26.3°s-1 to 1.1°s-1.Nonlinearity changes from 1.48%to 0.30%,angular random walk(ARW)is reduced from 2.19°h-1/2 to 1.42°h-1/2,and bias instability is improved by a factor of 7.7,from 197.6°h-1 to 25.4°h-1.     

The relation between generated power and losses in a gas laser

The relation between generated power and losses in a gas laser at 1.15 m has been determined experimentally. The data obtained confirm the possibility of computing the power within the framework of geometric optics. A method for determining the total losses in the resonator and the unsaturated gain is suggested.The authors thank B. I. Stepanov and V. S. Rubanov for valuable comments and suggestions.