In this paper a new technology of optic micro lens generated on needing positions is proposed. It is formed directly on
positions where the mocro-lens is mounted. The technique is easy, quick and cheap. It has application prospects in
astronavigation, military affairs, biology, chemistry and civil affair. In this paper fluid mechanics principle about the
optic micro lens generated on needing positions is researched. A surface equation set of optic glue drip, which spreads on
horizontal plane under surface tention, is given. The equation set reflect relations between coordinates of the surface
curve. A numerical calculation method of the equation set is proposed. Some shape curves and curvature radius curves
for different character parameters of the glu drip are given. Influences on shape of the micro lens through mixing
nanometer quartz powder in the glue drip and milling the glass are discussed.
Proc. SPIE. 8418, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Smart Structures, Micro- and Nano-Optical Devices, and Systems
In this paper a new manufacture technology of the micro-lens generated on needing positions is suggested. This
technology doesn’t need mould or masks, it generates the micro-lens on the needing positions directly according to
needing curve shape. It is a simple and quick laser micro-manufacture technology, which solves the difficulties of high
accurate separation the micro-lens from substrate and adhesion the micro-lens to working face coaxially. A microdetector
to fluorescence spectrum using the micro-lens generated on needing positions is made. The detector has many
advantages, for example high sensitivity and micro volume. It can be inserted in biochip, and it is used in alarm system
of harmful microbes in spacecraft also.
Coupled wave equation group of surface acoustic wave (SAW) acousto-electro-optic (AEO) effect are given and
correlative conversion efficiency formula is obtained. An collinear SAW AEO modulator with xy-cut lithium niobate
(LN) substrate is made. Curves of relative conversion efficiency vs electric power, direct current (dc) voltage and
frequency are measured. Additional dc voltages can change the center frequency of the modulator. This device has
applications in optic signal processing and optic communication.
Quartz crystal is a good piezoelectric crystal and it can be used as substrate of surface acoustic wave (SAW) devices.
How to cut the substrate crystal is important in design of the SAW devices, and the optimum cut direction is determined
by the direction of the largest electromechanical coupling coefficient. In this paper, SAW basic equation group
strengthened by piezoelectric effect and boundary condition equation group including mechanical boundary conditions
and electric boundary conditions are deduced. The electric boundary conditions have two kinds: free boundary condition
and short-circuit boundary condition. Two kinds of SAW velocities using the two kinds of electric boundary conditions
are systematically calculated for the quartz crystal respectively in decoupling of yz plane. The SAW velocities are
calculated using a circle iterative method, which calculation velocity is quick and calculation precision is high.
Electromechanical coupling coefficient is calculated using these two SAW velocities in yz plane of the quartz crystal.
Calculation results indicate that the maximum electro-mechanical coupling coefficient is 0.2885 at direction, which
makes an angle of 73° with y axis, in yz plane of the quartz crystal. The calculation results lay a solid foundation for
design and manufacture of the SAW devices.
Quartz crystal has excellent piezoelectric properties, it can be used as substrates of surface acoustic wave (SAW)
devices, for example delay line, filter, oscillator, convolver, acousto-optic (AO) device and so on. In this paper, Intrinsic
SAW basic equation group and SAW mechanical boundary condition equation group are deduced from character
equation of the crystal. Intrinsic SAW velocities are calculated using circle iterative method in three coordinate planes of
quartz crystal systematically. Stiffness coefficient of piezoelectric crystal can be changed by piezoelectric effect and it is
named as piezoelectric modified stiffness coefficient. Reciprocal velocity curves of quartz crystal in the three coordinate
planes using the non-modified stiffness coefficients and the piezoelectric modified stiffness coefficients are drawn
respectively. Configurations and periods of the curves are similar to projection figures of crystal lattice of the triangle
crystal system in same coordinate planes. It means that there is internal relationship between the SAW properties and
point group symmetries of the crystal. Research results lay a solid base for design and manufacture of the SAW device. It
has theoretical significance and practical value.
Proc. SPIE. 7658, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology
A cut direction, rotated ZY cut of Lithium Niobate (LN), is studied. LN is a good piezoelectric crystal and it can be used
as substrate of surface acoustic wave devices. In this paper, surface acoustic wave equations, including basic equations
and boundary condition equations, are deduced. According to these equations the surface acoustic wave velocities are
systematically calculated using a circle iterative method for LN along different directions in optimum decoupling
acoustic sagittal YZ plane. The electromechanical coupling coefficients for rotated ZY cut LN are also calculated. The
optimum cut direction of the LN crystal piece as substrate of surface acoustic wave devices is determined by the largest
electromechanical coupling coefficient.
In this paper a new optimum design method of anisotropic acousto-optic deflector (AOD) with ultrasonic beam steering
is introduced for two kinds of crystals: Tellurium Oxide (TeO2) and Lithium Niobate (LN). First anisotropic
acousto-optic (AO) interaction geometric relationships in the two crystals are calculated. Then optimum design method
and results, including design parameters and design curves of the two anisotropic AOD, are given through calculating
Bragg loss vs acoustic frequency. Final curves of relative bandwidth vs relative length for the two anisotropic AOD are
given. Compared with non-steering AOD, when relative bandwidth is equal to octave bandwidth, the relative length of
steering AOD will increase 34.7% for TeO2 anisotropic AOD and 73.4% for LN anisotropic AOD, when relative length
is satisfied condition into Bragg region, the relative bandwidth of steering AOD will increase 9.1% for TeO2 anisotropic
AOD and 17.7% for LN anisotropic AOD.
Lithium Niobate (LN) and Quartz. crystal are good piezoelectric crystals, they can be used bases of surface acoustic
wave (SAW) devices. In this paper, SAW elemental equation and corresponding mechanics boundary condition
equation are deduced. For the above two crystals, SAW velocities are calculated systematically, and curves of the
acoustic reciprocal velocity are drawn using a new circle iterative method in decoupling acoustic sagittal plane, that is
yz plane. Calculation results lay a good theoretical base for design of SAW devices and have research signification and
Wavelength encoding sensors, such as fiber Bragg grating, have the advantage of strong antijamming ability. However,
the wavelength encoding signal is usually converted into electric intensity signal by demodulators in most
measurements. The intensity signal is easy to be disturbed by environmental factors, so the advantage of wavelength
encoding fails due to the instable intensity demodulation. In this paper, a novel wavelength demodulating method is
presented. This method demodulates the wavelength encoding signal directly by means of counting using a Sagnac
interferometer with birefringent fiber without the encoding conversion from wavelength to intensity. Through the
interferometer, the changed wavelength signal from sensor becomes the kind of output light, the intensity of which is
changed with wavelength periodically. The intensity can easy be disturbed, but its period is very stable. In other words,
the change of wavelength in one intensity period is stable. With this character, we count the number when the rising edge
and falling edge of intensity appear, and then calculate the accurate change of wavelength signal. In experiment, we get
the 0.01 nm wavelength resolution by use of a Sagnac interferometer with 200 meter birefringent fiber. It can be proved
that the intensity frequency (the reciprocal of intensity period) changed with wavelength is proportional to the length of
birefringent fiber. The length is fixed, the frequency is determined. For farther increasing the wavelength resolution, it is
only necessary to increase the length of birefringent fiber. The wavelength demodulator by counting method has high
stability and high precision.
In this paper a strengthened acousto-optic (AO) coefficient of piezoelectric crystal is proposed. It shows the influences of AO effect, electro-optic (EO) effect and piezoelectric effect in piezoelectric crystal. Through correcting acoustic momentum mismatch into sum of the acoustic and electric momentum mismatch, the coupled wave equation group of the surface acoustic wave (SAW) AO effect can be changed as that of SAW acousto-electro-optic (AEO) effect. A diffraction efficiency formula of SAW AEO effect is given through solving the equation group. The formula indicates that the diffraction efficiency is related to power of SAW, acoustic frequency deviation and direct current (DC) voltage. We designed and manufactured a SAW AEO device using Lithium Niobate (LN). Some curves of relative diffracted efficiency vs power of electric signals driving the device, acoustic frequency deviation and DC voltage are measured. Experimental results are consistent with theory. SAW AEO device can be used as a deflector or modulator. When it is used as deflector, its bandwidth is wider than that of SAW AO deflector. When it is used as modulator, its center frequency can be changed. SAW AEO device has smaller volume, less energy consume and is easy to integrate. It can be used in optic communication and real time signal processing, for example correlation, convolution, spectrum analysis and optic vector calculation and so on.
A strengthened acousto-optic (AO) coefficient of piezoelectric crystal is defined. AO coupled-wave equations of surface
acoustic wave (SAW) to plane guide optic wave (PGOW) and to fiber guide optic wave (FGOW) are given respectively.
A diffractive efficiency formula of SAW PGOW AO interaction and a back-wave efficiency formula of SAW FGOW
AO interaction are given. The formulas indicate that under condition of weak AO interaction intensities of the
diffractive wave and the back-wave are proportional to ultrasonic powers. Lithium Niobate (LN) is optimum crystal of
SAW PGOW AO device, quartz is optimum crystal of SAW FGOW AO device. A SAW PGOW AO modulator using LN
and a SAW FGOW AO modulator using quartz are designed and manufactured. Some curves of the diffractive wave
power and the back-wave power vs. electric powers of signals driving the modulators are measured. SAW AO
modulators have many advantages, for example small volume, good stability, low energy consumption and it is easy to
integrate. The modulators can be used as intensity modulators. The modulators have applications in optic communication and real time signal processing.
Acousto-optic (AO) technology sprang up at the beginning of 1960s, after the naissance of laser. The electro-acoustic transducer is an important part of acousto-optic device (AOD), and quartz is an important crystal for making the transducer due to its good piezoelectric property. In this paper we calculated two kinds of acoustic velocities, non-strengthened acoustic velocities and strengthened acoustic velocities, for three kinds of acoustic modes, one longitudinal wave and two shear waves, in three coordinate planes of the quartz systematically using Christoffel equations. Then electromechanical coupling coefficients of every acoustic mode are calculated and curves of coefficients in three coordinate planes are pictured. Finally we determined the optimum cut direction of longitudinal wave and shear wave respectively. The results of this paper will play a directional role for the research of AOD.
It is well known that as a measurement device, Sagnac fiber interferometer has the advantages of high measuring
sensibility and strong antijamming ability. However, it is precisely because of the high sensibility, the measured change
range of sensed quantities is usually very small. And also because of the strong antijamming ability, the fiber of Sagnac
interferometer can not be used as a sensor. The reason is that the sensed signal well be eliminated by the signal
cancellation effect between the two directions in Sagnac interferometer like the disturbance signal. This paper presents a
novel Sagnac fiber sensor. It is added two devices into the common Sagnac fiber loop, one is the phase compression
device and another is the birefringent fiber sensor. The phase compression device consists of a time delay fiber and a
piezoelectic ceramic twisted around by Sagnac fiber. This device can realize the phase compression by which the
measured range of sensed quantities is widely extended. The birefringent fiber sensor consists of a short section of high
birefringent fiber. The method of adding the birefringent fiber sensor is selecting suitable position on Sagnac fiber loop
and breaking off the fiber, then melting and linking the two break surfaces with the short section of high birefringent
fiber. Not like the common fiber, there is not cancellation effect on the birefringent fiber. So the Sagnac interferometer
can become a sensor. This kind of Sagnac fiber sensor has the advantages of high measuring precision, wide measured
range, strong antijamming ability and simple structure.
Wavelength encoding sensors, such as fiber Bragg grating, have the advantage of strong antijamming ability. However,
the wavelength encoding signal is usually converted to electric intensity signal by demodulators in most measurements.
The intensity signal is easy to be disturbed by environmental factors, so the advantage of wavelength encoding fails due
to the instable intensity demodulation. In this paper, a novel wavelength demodulating method is presented. This method
demodulates wavelength encoding signal directly by means of counting using a Sagnac interferometer with birefringent
fiber without encoding conversion from wavelength to intensity. Through the interferometer, the changed wavelength
signal from sensor becomes the kind of output light, the intensity of which is changed with wavelength periodically. The
intensity can easy be disturbed, but its period is very stable. In other words, the change of wavelength in one intensity
period is stable. With this character, we count the number at the rising edge and falling edge of intensity appear, and then
calculate the accurate change of wavelength signal. From experiment, we get 0.067 nm wavelength resolution by use of a
Sagnac interferometer with 30 meter birefringent fiber. It is proved that the intensity frequency (the reciprocal of
intensity period) changed with wavelength is proportional to the length of birefringent fiber. If the length is fixed, the
frequency is determined. For farther increase of wavelength resolution, it is only necessary to increase the length of
birefringent fiber. The wavelength demodulator is characteristic of high stability and high precision.
In this paper, a fiber coupled-mode equation between front-wave and back-wave of optical guided modes with micro disturbance is given from parameter interaction equation. Considering surface acoustic wave (SAW) as the micro disturbance, a coupled-wave equation group of SAW all-fiber acousto-optic (AO) effect is deduced. The equation group includes front-wave equation and back-wave equation. A back-wave efficiency formula is demonstrated through solving the equation group. It is proved, that the back-wave efficiency is directly proportional to power of the SAW under condition of weak AO interaction. Quartz crystal is considered as the best base crystal. It is because acoustic impedances of the quartz crystal and the fiber are equal approximately. According to form of SAW basic equations or Christofell equations the best SAW mode of the quartz is determined. All-fiber AO intensity modulator using SAW is designed and manufactured. Modulation curve of optic power of the back-wave vs power of electric signals driving the device is measured. The experimental results indicate, optic power of the back-wave is directly proportional to power of electric signals driving the device. The experimental results are consistent with the theory. Advantages of the device are smaller volumes, less energy consumes, less inset-losses and so on. Besides, it is easy to integration and can be used in optic fiber communication.
Because of the characteristic of wavelength encoding, fiber Bragg grating (FBG) has the advantages of immunity to light
power fluctuation, variation in polarization and connecting loss, so it has high sensing precision. However, for the
demodulation of FBG, wavelength signal is usually converted to electric amplitude signal. By measuring the amplitude
signal, the sensing result is obtained. It is well know that the amplitude signal is easy to be disturbed in sense. For this
reason, amplitude demodulation limits the effect of wavelength encoding of FBG. This paper presents a novel method of
counting wavelength demodulation for FBG sensors using a high birefringent fiber (HBF) loop mirror. This demodulator
has simple structure, high precision, low cost and convenient to use. The resolution of the loop mirror device with 30
meter long of HBF is 0.067 nm. This counting wavelength demodulating method has the significance for widespread
practical application of FBG sensors.
In this paper the beam steering theory in isotropic acousto-optic (AO) device is studied. In the process to design an AO deflector, it is important that the device has wider 3db Bragg bandwidth and uniform diffraction efficiency in frequency band. According to the theory about isotropic AO interaction, we can obtain wider 3db bandwidth by using technology of ultrasonic beam steering. It means, the momentum match condition can be satisfied at two track frequencies. The author gains the optimum track frequencies for various numbers of transducer pieces in plane and step configurations respectively. Based upon this argument, farther on, the optimum design parameter of the isotropic AO deflector is also shown up.
A high-sensitivity fiber Bragg grating (FBG) pressure sensor has been designed and studied. Confining some gas inside a glass cylinder with a close glass piston which can move smoothly along the cylinder, and sticking two ends of a fiber Bragg grating on the outer side of the cylinder and piston respectively. The variation of the external pressure results in the change of the tension that the fiber grating is subjected to and then the pressure can be measured by the measurement of the Bragg wavelength of the FBG. The pressure sensitivity coefficient is up to -0.7676/MPa, which is about 3.88×105 times the value of bare fiber Bragg gratings, the highest sensitivity ever reported. The sensor can be used to potential applications in the measurement of air pressure, hydraulic pressure and vibration in the range of low pressure.
In this paper we researched principles of three-dimensional (3-D) isotropic acousto-electro-optic (AEO) modulator, including coupled wave equations and diffraction efficiency formula of the 3-D AEO effect. The AEO crystal is worn into a column of six side-faces. Three transducers are stuck on adjacent side-faces and they can produce three acoustic energy channels of 60° each other in acoustic plane. Direct current (DC) electrodes with central holes are plated on the end-faces. Through the hole, incident light propagates along axis of the column, which is perpendicular to the acoustic plane. So the acousto-optic (AO) effect must be Raman-Nath effect, it can realize 3-D light deflection. The DC electric field is supplied along the axis of the column too. So the electro-optic (EO) effect must be longitudinal, it can realize light modulation. We designed and made a 3-D isotropic AEO modulator of centre frequency 50 MHz using Potassium Hydrogen Phosphate (KDP) crystal, and measured its modulation curve of relative diffraction efficiency vs DC voltages. Measured results agree with theoretical calculation. Multi-dimensional AEO modulator has applications in multi-channel optic communication and optic signal processing.
A TDM FBG sensor system with CCD detection was presented for a serial FBG array. Four FBGs were multiplexed and a device based on NOLM technique was adopted for the separation of the pulses. Computer simulation shows that the system provides high sensitivity which is the main factor for a practical FBG sensor.
In this paper longitudinal electro-optic (EO) effect and multi-dimensional isotropic Raman-Nath acousto-optic (AO) effect in square system and cubic system are researched. KDP of the square system and GaP of the cubic system are chosen as crystals for multi-dimensional isotropic Acousto-electro-optic (AEO) devices. Through calculation of function characters of multi-dimensional isotropic AO interaction in the two crystals, optimum operating modes are determined for their two-dimensional (2-D), three-dimensional (3-D) and four-dimensional (4-D) isotropic AEO effect. The research results will lay the foundations for design and manufacture of the multi—dimensional isotropic AEO device.
In this paper coupled wave equations of acousto-electro-optic (AEO) effect are proposed. These equations are based on coupled wave equations of electro-optic (EO) and acousto-optic (AO) effects. A formula of diffraction efficiency of the AEO effect is given through solving these equations.
The method to perform matrix/vector multiplication using the acousto-optic (AO) processor has been studded in some earlier publications. This processing architecture provides high speed and high accuracy calculation. However, in the system, two AO devices must be used. For this reason, the optical couple between the two devices has to be adjusted carefully. It will cause the inconvenience and unsteadiness. A novel two- dimensional multichannel acousto-optic device is presented in this paper. By use of this kind of device, the trouble which the earlier architecture suffered from is got rid of and the experiment system is simplified.
In this paper two-dimensional and multiple dimensional acousto-optic interactions are studied. The sets of coupled wave equations of multiple dimensional acousto-optic diffraction with multiple acoustic waves along different directions is put forward and its solutions are derived. The characteristics of the diffraction efficiency, compression, cross modulation, and intermodulation intensities are analyzed theoretically. The theoretical results are supported by experimental measurements through our new type of multiple directional acousto-optic modulators.
A set of coupled wave equations for two-dimensional multichannel acousto-optic interaction is set up, and its solutions are derived. The characteristics of the two- dimensional multichannel acousto-optic interaction are analyzed theoretically. A new type of two-dimensional multichannel Bragg acousto-optic modulators are made, and its characteristics are measured. The theoretical analyses are supported by experimental results. The matrix-vector multiplication operation can be performed by our two dimensional acousto-optic multichannel modulator.
Because optical calculation has advantages of high speed computation, parallel operation and high capacity, it attracts considerable attention and rapidly develops recently. This paper presents an acousto-optic (AO) convolver by which the digital multiplication is performed.