The synchronous paragenesis of piezoelectric resonance together with EO modulation,
its effect on the electro-optic probing in low frequency range, and a new voltage calibration
technique which can utilize the piezoelectric resonance to enhance the voltage sensitivity of EO
probing, are reported for the first time.
Exact expressions for calculating the electro-optic (EO) coefficients of GaAs and polymer or organic/inorganic hybrid
film using simple reflection technique have been deduced. For different approximate conditions, several expressions
have been contrasted. After strictly verified, the measuring systems are accurately adjusted, and with the measured data
the numerical value of
γ33 can be calculated. The measured EO coefficient of GaAs is in excellent agreement with the
known value. The organic/inorganic hybrid material is prepared by sol-gel process during which dispersed red 1 (DR1) is
doped in tetraethoxysilane (TEOS) as the chromophore with a concentration of approximately 13% by weight. And
of hybrid material over 20pm/V could be easily obtained.
Highly transparent TiO2/SiO2 films prepared using sol-gel technique doped with organic azo dye, Disperse Red 1(DR1)
have been investigated. Processing parameters such as spin speed, spin time, and ambient atmosphere, and solution
synthesis parameters such as catalysis method, alcohol dilution ratio, and component molar percentages, may affect the
film formation. The refractive index increases follow along with the raising of the molar ratio between TiO2 and SiO2.
When the molar ratio between TiO2 and SiO2 is zero, i.e. no titania precursor in the initial solution, the refractive index is
minimum 1.49 at 1300nm, whereas when there is no TEOS in the initial solution, the refractive index is maximum 1.81
at 1300nm. The sol-gel thin film is spin-coated on ITO glass substrate with better uniformity. The electric-optic
coefficient γ33=42pm/V was measured by simple reflection technique at a fundamental wavelength of 1300nm. The
hybrid organic-inorganic sol-gel film is well balanced material in its simplicity for film formation, nonlinearity, and
thermal stability sufficient for device fabrication. Moreover, the measurement system was calibrated and the measured
electric-optic coefficient of the gallium arsenide crystal is in excellent agreement with the known value.
A method for measuring the electro-optic coefficient of poled polymer films on the basis of an asymmetry Fabry-Perot cavity is described. Two aluminum films were deposited on glass substrate by thermal evaporation in high vacuum to form high reflection mirror and low reflection mirror, respectively. Nonlinear polymer thin films are spin coated on low reflection mirror and poled by corona poling in order to break the internal centrosymmetry. Then the sample layers are placed upside down on the high reflection mirror. The sandwich structure is objected to a laser beam, and a variable voltage is applied the aluminium films resulting in a modulation of the transmitted laser power. The electro-optic coefficient γ13 of the poled polymer film can be calculated by evaluating the Fabry-Perot equation. The spatial resolution is tested with a polymer film that was poled by a needle corona discharge in air through a metal grating with a period of 120 microns. By scanning the sample plate in the direction perpendicular to the grating lines, the spatial resolution is also demonstrated according to the spacing of the poled structure.
A new rnethod, based on zero point of longitudinal electric field, was used to deterrnine the spatial resolution of electro-optic (EO) probing systern. To examine the spatial resolution of internal and external EO probing systems, an interdigital structure is fabricated on GaAs substrate with and without a layer of Si02 between the electrode and the substrate respectively. Considering Si02 layer or air gap between electrode and EO crystal, the result of electro-optic probing was simulated which is well accorded with experiment. The result indicates that spatial resolution of less than 0.5um and lum are obtained in internal and external EO probing system respectively.
Based on the arrayed waveguide grating (AWG) multiplexer theory, some important parameters are optimized for the structural design of a polymer AWG multiplexer around the central wavelength of 1.55μm with the wavelength spacing of 1.6 nm. These parameters include diffraction order, focal length of slab waveguides, number of arrayed waveguides are determined. Then, a schematic waveguide layout of this device is presented, which contains 9 input and 9 output channels. The transmission and loss characteristics are analyzed. The computed results show that when we select the core thickness as 4 micron, width as 6 micron, pitch of adjacent waveguides as 26 micron, diffraction order number as 78, distance between the focal point and the origin as 8340 micron, the total loss of the device can be dropped to about 5.7dB, and the crosstalk among output channels can be dropped below -50dB.
In this paper, the basic principle, details of fabricating process and measuring results were described for a polymer/Si arrayed waveguide grating (AWG) multiplexer around the central wavelength of 1.550 micron with the wavelength spacing of 1.6nm. The fluorinated polymer was used to fabricate AWG to reduce the optical loss, but the fluorinated material was expensive, so we initially adopted the polymer of polymethylmethacrylate(PMMA) type to go on technologic research. The regulated curve of refractive index was given for the core polymer. In order to obtain better shape of the waveguide after the reactive ion etching (RIE) using oxygen, an aluminum film as mask was used on polymer instead of conventional photoresist as mask. In order to reduce radiation loss of underciadding layer to Si
substrate, the underciadding layer thickness was increased to 11 micron through two times of spin-coating, thus the radiation loss was reduced to the order of 0.001dB. The measuring results indicates fabricated optical waveguide achieved single-mode transmission.
In this paper, a 9 X 9 Polymer/Si AWG was designed and fabricated. The cladding material is poly-methyl-methacrylate-co-glyciclyl methacrylate (PMMA-GMA) and the core material is the mixture of
PMMA-GMA and bis-phonel-A epoxy. During the fabrication process of the Polymer/Si AWG device, We used aluminum as mask on polymer instead of conventional photoresist as mask. The results show that the device is good for the wavelength division multiplexing (WDM) system. The output characteristics of the device were measured by a system based on the tapered fiber. The results show that our polymer/Si AWG meets the designed device well.
We use a new impedance graded line that is backland coplanar wave-guide to design transmission line. During the permission of measurement scope on project, we can perform arbitrarily matching for 5(Omega) approximately 75(Omega) , calculated in the method of quasi-static analysis, using the microwave matching network and high-frequency encapsulation, we can improve our work frequency and effective power effectively.
Electro-optic modulation has been first demonstrated using a poled electro-optic polymer films, placed in a Fabry-Perot cavity. In our configuration, incorporating an electro-optic material in the spacer layer of a Fabry-Perot device creates such a structure whose optical transmission characteristics depend on the applied voltage. And the longitudinal electro- optic modulation, in which the direction of the poling electric field, the applied electric field and the light traveling are parallel with one another and perpendicular to the surface of the polymer film, is applied. According to the electro-optic tensor of a poled polymer film, there is no birefringence effect and only phase modulation of the light is produced. Considering the interferometric nature of the Fabry- Perot cavity, the phase modulation can be converted to the amplitude modulation. The cavity used had a finesse of about 20. The thickness of film is about 1 micrometers . The modulation depth achieved was about 0.07% for a low ac field of 1V/micrometers . The results are promising for the study of array modulation and optical interconnection.
Conditions to reconstruct pulse intensity and chirp from autocorrelation signals are discussed. The interferometric SHG autocorrelation signal and the interferogram of fundamental light are shown to be sufficient data set for the pulse form retrieval. The method utilizes Fourier analysis of the signals and iterative calculations.
In this paper an external electro-optic measuring system based on a hemispherical GaAs probe is presented. By using the system, the electrical signals propagating on a microstrip transmission line are successfully measured. The spatial resolution of the system, which is limited by the focused probing spot size, is about 0.5 micrometers , when the wavelength of the probing beam is 1.3 micrometers .
A second-order nonlinear optical polymer was synthesized with bis-phenol-A as the polymer backbone, p-nitroaniline as the chromophore and cinnamyl group as the photo-sensitizer. The polymer films were obtained by spin-coating and poling by three methods respectively. These methods of poling include needle electrode corona poling, parallel wire electrode corona poling and contact poling, which were used to obtain the molecular orientation. The uniformity of the side-chain polymer films have been studied by external electro-optic measurement. The spatial resolution of system is 3 micrometers . Experimental results demonstrated that parallel wire electrode corona poling is easier to obtained large poled area with good uniformity than that of other methods.
Selective proton bombarded buried stripe lasers have been developed using the tungsten filaments as a mask to proton bombard the current-blocking area. High reliability has been shown in high temperature accelerated aging tests. For the selective proton bombarded buried crescent laser diodes, the output power of 150 mW, the small signal modulation bandwidth in excess of 11 GHz for the 250 micrometer cavity length and full area electrode, and the shortest gain switched laser pulses of 7 ps FWHM by combined DC and microwave current injection are achieved.
Introduced the construction of the experiment system of the laser probe measurements based on electro-optic sampling technique. Analyzed the relationship between the width of the optical pulses and the signal noise ratio of detection. The function of different stage circuit internal to the high-speed dynamic divider circuit chip have been measured with the double-frequency phase sweeping technique. A detail analysis about the chip failure have been given.