The temperature-dependent polarization error occurred in the silica waveguide ring resonator (WRR) is a major factor that limits the long-term performance of resonator integrated optic gyro (RIOG). In this paper, the temperature characteristics of transmissive silica WRR are successfully measured using the experiment system and analyzed in detail by us. According to the experiment results, we accurately calculate the temperature-induced refractive index and birefringence variation coefficient of silica waveguide, and we have found that the interference dip and peak of resonance curves will appear alternatively in the period of temperature fluctuation, which had not be shown before.
Proc. SPIE. 9685, 8th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems; and Smart Structures and Materials
At present, the splitting ratio test of the waveguide coupler usually adopts optical fiber coupling test method. The coupling process is complex and the coupling loss is different in two pigtail fibers, what can result in error in the splitting ratio. A new method for testing the splitting ratio of waveguide coupler using laser beam profiler is presented. Laser beam profiler is used to scan the horizontal directional light field in the cross-section of the waveguide. The measurement data are obtained. Data fitting and processing is carried out by data processing program. Finally, two light field curves are gotten, and the splitting ratio of the waveguide coupler is calculated. The feasibility of the new method is verified using fiber coupler. The error using the new method is only 0.68%. The waveguide coupler testing platform is built. The relationship between the measurement range of the splitting ratio and the minimum distances of the waveguide coupler is analyzed. The research provides an effective and convenient method for the test of splitting ratio of waveguide coupler.
A closed-loop resonator integrated optic gyro (RIOG) scheme based on triangular wave phase modulation is proposed.
Only one integrated optic modulator (IOM) is employed. Triangular wave is applied on the IOM to modulate the passing
light wave, and the feedback serrodyne wave is superimposed upon the triangular wave to compensate the resonant
frequency-difference. The experimental setup is established and the related measurements are performed. The results
show that the proposed scheme can realize the closed-loop RIOG employing an IOM, which has the advantage of
miniature size. A bias stability of 0.39 deg/s (10 s integration time) over 1 hour is achieved. Moreover, good linearity and
large dynamic range are also experimental demonstrated.
Based on the Sagnac effect, a resonator micro-optic gyro (RMOG) is a novel optical sensor used for measuring rotation velocity. Due to the advantages of small volume, narrow linewidth, and tunable wavelength, an external cavity laser diode (ECLD) is adopted. By analyzing the working mechanism of the ECLD, a new scheme of constant temperature and driving current tuning control is determined. First, a theoretical resonance curve is calculated. Then the laser frequency is successfully tracked in the RMOG. Finally, a bias stability of 1.6 deg/s over 600 s is obtained in the RMOG with a silica waveguide resonator of 12.8 cm.
A novel actuator of small angle control is researched and designed in this paper, which can be used in micro optical
electro-mechanical system (MOEMS) gyroscope. This actuator is composed of three pieces of piezoelectric ceramics
(PZT), foundation base and gear frame. According to converse piezoelectric effect, dilations of the PZT change when
applied voltages are different which leads actuator to have a deflection angle. Connected with control circuit, actuator
has the ability to exactly adjust angle which has arc-second level. It can accomplish the adjustment of spatial resonator
with high efficiency. Structure model of the actuator was set up, and simulation was completed in this paper. Also the
performance of actuator was validated by experiment.
The application of SOI wafer in integrated optical components provides a novel method of increasing the density of
integration, as well as reducing unit cost. This paper designed a new kind of waveguides coupler for an integrated optical
transceiver unit of an interferometric fiber optic gyroscope system. Based on effective index method and beam
propagation method (BPM), mathematic model of the waveguides coupler was founded, and theory calculation and
analysis were finished for key parameters, such as coupling ratio, effective coupling length, division radio and returning
loss, etc. Also these parameters were optimized in practice coupler design which used in integrated optical transceiver.
The design results indicated that its division radio is 50%:50%, coupler core size is 6μm×5.5μm, length of the chip is
25mm and width between two export ports of the waveguides is 400μm. With electron beam lithography machine the
mask of silicon-on-insulator (SOI) waveguides coupler was fabricated. The mask fabrication parameters were developed
and optimized in this paper. Detect results shown that this optical waveguides coupler can be used in integrated optical
transceiver unit for the interferometric fiber optic gyroscope system. This result can provide significant theory basic for
research on high integrated, high reliably, low cost integrated optical components used for interferometric fiber optic
MOEMS (Micro-Opto-Electro-Mechanical System) gyroscope is one of the research hotspot of international inertial
domain. It combines advantages of optical detect principle of optical gyroscopes and MEMS (Micro-Electro-Mechanical
System) fabrication technique. It is solid-state. It has little volume, light weight, good stability, and large dynamic scale.
And it can be batch fabricated. These make it has large applications in inertial technology domain. A MOEMS
interferometric gyroscope which uses spatial optical paths to sensitive Sagnac effect is presented. A spatial helical
optical structure composed of micromirrors was designed. Light traveled in free space, which could reduce wastage. The
gyroscope has no coupling problem, no back scatter, and no movable parts. The structure of the gyroscope has
advantages in microminiaturization. It could be manufactured using MEMS technics. Theoretical analyses were made to
parameters of the spatial optical path from the viewpoint of improving the fundamental detection limit. Theorem proving
experiment was researched. Based on experiment design, output signals of the gyroscope on rotate platform were
measured using Lock-in amplifier and other instruments. Theorem proving of the Sagnac effect is realized, and the bias
stability of the gyroscope system is about 8 °/h.
In contrast to null compensator method in aspheric surface testing, a novel method is presented that uses part-compensating lens and digital moire phase-shift interferometry. Researches are made on measurement principle, design method of part-compensating lens and calibrating lens, and calibrating method. Experiment is made by using spherical surface to simulate aspheric surface testing. The measurement precision is that the P-V value of the testing error can be λ/10. Using the method presented in this paper, the structure of compensator is much simpler than that of null compensator. And one part-compensating lens can be used to test different aspheric surfaces in certain range.
A novel aspheric surface testing method using part-compensating lens is presented in this paper. Researches are made to the specific design requirement and design method of part-compensating lens. The design requirement is applied in the optimization design of the part-compensating lens to three kinds of aspheric surfaces, and it is proved that the structure of part-compensating lens is much simpler than that of null compensator. Analysis is made about the asphericity compensation range of each part-compensating lens, some range can be 30 λ. The results demonstrate that aspheric surfaces with different relative aperture and asphericity can be compensated by part-compensating lens that is simple and easily fabricated, and the shape error of aspheric surfaces can be measured.
The new generation’s so-called intelligence “virtual testing”, the combination of computer technique and testing technique, comes into being. Virtual testing makes use of advanced virtual instrument technique, changes the original work that can be completed by traditional optical instrument hardware. Virtual testing can decrease the request of hardware, simplify the instrument construction, decline cost and increase testing precision at the same time. Aspheric surface plays an important role in modern optics. But the accuracy of traditional testing methods can’t meet the demand. Testing methods become the key of application of aspheric surface. In the paper virtual testing technique is applied at aspheric surface testing and the result shows that the technique can improve the testing precision.
A computer-aided alignment method is put forward in this paper. It combines laser shearing interferometry and computer- aided optimization, accurately measures the alignment of the optical elements of the system being aligned and gives the adjustment project to control the wavefront quality. The theoretical analysis and experiments demonstrate the ability and effectiveness of this computer-aided alignment method and it especially suits for the on-site alignment of large and complex optical system.
The Global Explorer (GE) algorithm proposed by Isshiki is implemented in the GOLD program developed by Beijing Institute of Technology. Global optimization with GE consists of many local optimization runs with or without the escape function using the damped-least-squares method. In order to improve the efficiency of the local optimization, two search schemes are incorporated into the program. The first one searches for the best damping factor which effectively determines the optimum direction of the solution vector in the multi-dimensional variable space, and the second search is conducted along that direction to find the optimum length of the solution vector. Experiments are also made to determine the optimum default values for the parameters of the escape function.