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This paper presents a novel technique to improve the design and implementation of in-fiber components by providing real
time control of cladding removal by either polishing or etching. Cladding removal allows interaction between external
materials and devices, and the light propagating in the fiber.
Monitoring of the cladding removal process is achieved by observing the output from a section of fiber into which laser
light has been focused. Resulting output graphs show that each specific fiber produces characteristic oscillations dependent
on the number of modes propagating, the thickness of the cladding, the birefringence of the fiber, and the initial
polarization state of the light. These oscillations result from changes in the effective indices of refraction of different
modes as the cladding is removed.
Electron micrographs of etched fiber surfaces show that unless proper cleaning and handling techniques are followed, the
etched surface is scarred and pitted, leaving a poor quality substrate for device applications. However, if careful cleaning
techniques and buffered hydrofluonc acid are used, the presence of these defects is drastically reduced and the resulting surface
is smooth on a sub-micron scale.
In order to understand better the characteristics of etched or polished fibers we have extended existing theoretical models
which predict the effect of cladding removal on fiber birefnngence. Corroboration and use of these models allow more
reliable monitoring and control of variables in the etching or polishing process such as cladding thickness, fiber alignment,
acid concentration and temperature, and indices ofrefraction from fiber to fiber.
Using the techniques presented in this paper, diffraction gratings are fabricated in etched D-type fibers. Other possible
applications for this work include the production of variable wave plates, mode discriminators, polarizers, and the
placement of detection and signal conditioning devices directly on the surface of a fiber.
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It is well known that single mode and polarization maintaining fiber
couplers are strategic comoonents An both communication and sensor app1
icat ions.
We present here an automatic unit capable to produce fused single mode
and polarization maintaining fiber couplers having a high degree of
splitting ratio reproducibility and stability against environment
variations.
The development of the couplers production takes origin from the ac-
tivities pertaining to fiber optic interferometric sensors (gy-
ruscopes and hydrophones).
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A distributed fiber optic temperature sensing system was developed which
consisted of a high-resolution optical time domain reflectometer (OTOR) and a
special optical fiber sensor. Several 1 kilometer lengths of prototype
sensing fibers were formed by coating a modified, ultraviolet light curable
polymer cladding material onto a core glass during fiber production. By
monitoring changes in Rayleigh backscattered light from the fiber; local
temperature changes were measured along the fiber length. A demonstration
system was assembled with a 20 meter sensing fiber and extensive data were
collected. These measurements indicated that hot spots as small as 10 cm
could be detected over a temperature range of 0 to 150°C with a measurement
accuracy of ±°C
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This paper describes architecture and performance of a fiber op-
tic gyro based on a closed loop configuration, and an integrated
optic device associated with a fused type polarization preserving
fiber coupler.
Experimental results for open loop and closed loop operation are
reported, with reference to behaviour under thermal stress
condition.
The 1.0. chip project methods are described ,reporting also the
optical performance of the device and the inherent problems.
At last general systemistic considerations and prospects of in-
dustrial solution of the problems still open are given.
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The double crucible with 20 nozzles contains two separate concentric crucibles
with 20 nozzles on the bottom of each. Upper-side crucible is used to melt core
glass and bottom-side crucible to melt cladding glass. There is a space between
the two crucibles. Nozzles are welded on the bottom of each crucible. They are
formed into 20 couples correspondingly and each couple of nozzles are assembled in
the manner of transition fit. In order to get even thickness of cladding the
tolerances between each couple of nozzles should be controlled minus 0.025mm along
the direction of axis of each nozzle. The bulk glass ( F-13 and N-2 ) is heated in
crucibles until it is soft enough to flow through the nozzles and meet together
just on the end of nozzles. Then it is drawn directly onto a cylindrical drum of
approprite diameter. Considering the fluctuate of the fiber diameter caused by the
variation of temperature in crucibles and hight of the melted glass, two premelting
chambers were designed. After bulk glass is melted in the premelting chambers, the
melted glass flows through a hole into the double crucible. The flow should be
stable and even if the diameter of the hole has been chosen correctly.
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There are three know-hows in the drawing of plastic optical fibers with 36
nozzle die head: the design of 36 nozzle die head, the synchronous coating of 36
filaments and the 36 filament forming technology.
The most difficult problem to be solved in the drawing of plastic optical
fiber with 36 nozzle die head is the design of 36 nozzle die head. In other words,
the die head has direct influence on the drawing process. The second important
know-how is the techniques of synchronous coating of 36 filaments because the even
extent of the cladding (coating), the state of the core-cladding intersurface and
the thickness of the cladding have direct influence on the transmittance of the
plastic optical fibers, too. Careful design of the drawing procedure is another
important know-how in the manufacturing of plastic optical fibers.
To use the 36 nozzle die head to manufacture plastic optical fibers, not only
the efficiency of production can be highly increased and the cost can be largely
decreased, but also the technology makes it much easier for us to produce plastic
optical fiber's light guide and image guide directly.
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Finite difference and finite element methods, and the coupled mode theory are
combined to study in detail the ion-exchanged glass channel waveguides. Ordinary
and grating assisted waveguides are analyzed. The effect of various device
parameters on waveguide behavior is investigated. Design curves to make waveguides
with required characteristics are provided.
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An integrated optic consisting of buried diffraction gratings and a planar waveguide was developed as an internal
reflectance element for broad-band spectroscopic analysis of liquids. Polystyrene or tantalum pentoxide waveguides were
deposited over a pair of diffraction gratings etched into the surface of a glass slide. Multiwavelength light was focused
through the substrate onto the first grating. Component wavelengths were coupled into the waveguide and spatially
dispersed by the second grating after propagating through the waveguide. A silicon photodiode array detector was used to
collect the spectral data. Our goal is to produce a compact, rapid spectrometer having no moving parts that can take
advantage of fiber optics and fast array detectors in the visible and near-infrared regions for industrial process control. The
thin planar waveguide provides enhanced sensitivity to analyze weaker absorptions in the near-infrared.
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We report the first electro-optic switching device compatible with multimode fibers. A 1-to-many
cascaded reconfigurable interconnection was built.
A thin glass substrate was used as the guiding medium which provides not only higher coupling efficiency
from multi-mode fiber to waveguide but also better tolerance of phase matching conditions. Involvement
of a TIR hologram and multi-mode waveguide eliminates interface problems between fibers and
waveguides. The DCG holographic material has proven to be reliable from -180°C to +200°C.
Survivability of such an electro-optic system in harsh environments is further ensured. LiNbO3 was
chosen as the E-O material becuase of its stability at high temperatures (phase transition temperature
>1000°C) and maturity of E-O device technology. Further theoretical calculation was conducted to
provide the optimal interaction length and device cpacitance.
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Cesium, potassium and silver ion-exchange processes in three
commercially available soda-lime and Nd-doped glasses are investigated
for waveguide fabrication. A spin-coating technique is employed to
make Er- and Nd-doped phosphate layers on the waveguides in soda-lirne
glass. Transmission, absorption and emission properties of the
waveguides are studied. Optical amplification in Nd-doped waveguides
is demonstrated.
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We present the electrical behavior of an integrated
waveguide/photodetector based on the absorption of the evanescent optical
field in an absorbing layer, deposited on the top of the waveguiding layer. We
establish the expression of the electron-hole pair generation rate, for such a
device. Then, we apply this result to the calculation of the dynamic quantum
efficiency of an integrated waveguide/PIN-photodiode. The static and dynamic
behaviors of GaInAs PIN-photodiodes monolithically integrated on a classical
n/nt InP homostructure waveguide or on a GaInAsP/InP heterostructure
waveguide are discussed and optimized structures are pointed out.
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The development process resulting in a pulsed thick film IR emitter is described.
Various configurations are discussed, including resistor and substrate variations, as
well as packaging limitations. Test results are reported that indicate failure mechanisms
overcome, including high current density and high temperature, as well as material
migration and resistor degradation. Mechanical constraints and design configurations are
also discussed. Current emitter design allows modulated operation from 500°C to 600°C
at 40 to 100 Hz for periods in excess of 10,000 hours. Test results on newer materials
indicate that peak temperatures and modulations twice that are feasible. Other potential
applications are discussed.
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In this paper an attempt is made to study the influence of photon
energy on the photoernission from nonlinear optical materials from ultrathin films, cj,uantum well wires, quantum dots of the said
material on the basis of a new dispersion law considerir all types
of anisotropies of the band parameters within the framework of E'
formalism. We have studied the photoeriisson from bulk specimens
and also under the influence of an arbitrarily oriented quanti zing
magne tic field in the same material tak ing n-C dGeAs as an example for the purpose of numerical computations. It is found that the
photoemission increases with increasing carrier concentration non-
linearly in all, the cases an oscillates with inverse magnetic
field. The photoemission also increases with the incident photon
energy, in a ladder like manner and exhibits oscillatory dependen- ces with Changirg film thickness in all types of quantum confine-
ment. The well known results of three-band Kane model, two-band Kane model and that of parabolic model of nonlinear optical mate- rials have been obtained as special cases of our generalized
theoretical formulations. The mathematical analysis is in agree- ment with the experimental observation as reported elsewhere.
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Mode locking of a laterally UV prelonized discharge XeC1 laser
has been obtained by using a phase conjugate mirror as full reflector
in the laser cavity. The phase conjugate mirror via stimulated Brilbum
scattering presents a time dependent reflectivity. It acts as a
modulator and provides amplitude modulation at the cavity round trip
time. An output beam made of 5 short pulses separated by 10 nsec has
been obtained. The shortest pulse is 2 nsec FWHM long.
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Photorefractive gain is measured in poled, 1% tantalum-doped Potassium Niobate (KNbO3).
Two-wave mixing experiments are presented which exploit the '42 coefficient of KNbO3 by employing
non-symmetric geometries which rotate the grating vector away from the optic axis. The effect of this
rotation on the exponential gain coefficient is shown. Experimental results are compared to an analytic
expression derived for this parameter. The experiments were performed using an Argon laser
stabilized at =51 4.5 nm. The light was extraordinarily polarized and ihe beams were incident on the
b-face of the crystal. The absorption and the response time of the crystal were measured. Losses due
to scattering and self-pumped phase conjugation were also investigated.
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The focusing of a neutral atomic beam using near-resonant laser light is considered. The
results of a path integral solution to the Schrodinger in the stationary phase approximation
are presented. The details of the derivation of the propagation kernel are presented elsewhere
[1]. This approach is general and allows us to deal with "thick" laser lenses. Numerical
results for the focusing of a Gaussian atomic beam are presented. These results show
that spot diameters on the order of 20 Angstroms are obtainable for many reasonable
choices of laser and atomic beam parameters, and that for most of these cases the thin
lens approximation is not valid.
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The quality of solder joints on printed circuit board (PCB) is directly related to the reliablity and stablity
of electronic products. How to ensure the quality of solder joints? One necessary step in production is the
inspection of defective solder joints. In this paper, an automatic holographic interferential inspection method
on PCB solder joints is presented. Based on this method, the inspection system ,which includes three parts --
Optic imaging system(OIS), Automatic control system(ACS) and Processing and recognition system(PRS),
has also been discussed. A series of interferential fringe image processing algorithms are put forward and discussed
at the end of the paper.
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The dynamical behaviours of an intracavity modulating laser with feedback device are discussed in
this paper. Some of modulating methodes, such as electro-optic, acousto-optic and magneto-optic
modulation etc., are introduced, and the outputs of that laser are analysed in detail, which show that
output could be multistability, instability and chaos.
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Both cat and ring self-pumped phase conjuqators have been realized in Ce--doped
potassium niobate (KNSBN) crystals at 632 8nm by using lie-Ne laser The phase
wit ies of 4(J% and 50% were measured respectively Some characteristics of the
were studied experimentally
barium strontium
conjugate reflecti-
phase conjuqaturs
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The process of growing large diameter and lower residual infrared absorption
single crystals of Al203:T13+ by a new growth technique named induction field up-
shift method (IFSM) is described, and some of the problems in producing high laser
quality single crystal are discussed using different techniques have been given.
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The authors developed a high-performance magnetic and optical complex sensor unit
used for applications requiring high security, such as discrimination of notes,
cards, etc.
This new sensor unit has a sensor head constructed of a magnetic head and a
reflective-type photo sensor embedded in a small gap of the magnetic head. And
enables correct pattern recognition by optical information obtained together with
conventional magnetic information.
Traveling this sensor head in contact with the surface of the subject of discrimination
can detect difference of reflectance at the same time as the magnetic
detection at the same point of place.
As a result it became possible to discriminate for example, bills of any size in
any country.
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The field of melrology always seeks increasingly accurate, high resolution absolute measurement
devices having a fast frequency response. This has driven the field of linear position measurement to accept
compromises to achieve the one most desired feature for a particular task at the expense of the other
features. These compromises usually take the form of trading speed and/or absolute position information for
accuracy with incremental position information; or trading accuracy and/or speed for absolute position
information . To try and eliminate these compromises, an absolute linear position encoder was built using a
linear C.C.D., a small high-intensity area infra-red light source, a new simple absolute scale, and a digital
signal processor (for image processing, temperature compensation, and calibration compensation). The
prototype encoder has a measurement distance of 500 mm, and a measurement resolution of 1.0 im at
measurement update rate of 1 kHz or 0.1 jtm at 15.6 Hz. The mechanical backlash or short term
repeatability of the device was found to be a total of 1 pm. This device was then calibrated and checked with
respect to an Hewlett Packard 5528A laser interferometer. The encoder proved to be accurate to within
5.0 tm over the 500 mm length or to have more than 16 bits of accuracy. It is clear that this new type of
absolute linear position measurement technology eliminates many of the above mentioned compromises of
the past by combining relatively high speed, high resolution, high accuracy, temperature compensation, and
absolute position information in one measurement system.
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A hybrid intensified CCI) tube, based on a moulded thinned backside-bombarded CC'!) sensor
(604x288 pixels) has been achieved for applications of very low light level imaging and twodimensional
photon counting.
The CCD is a modiflcd version of the Philips NXA 101 1 FT sensor, moulded in a ceramic/glass material
before thinning, so that the sensitive area remains flat, frontside supported and thermally stahilized.
Materials are fully compatible with ultra-vacuum technological constraints and with the
presence of alkalis incorporated during the photocathodc growing process.
In this paper, the main results of electron detection experiments with thinned CCI)'s are displayed,
both obtained in scaled tubes and in a Scanning Electron Microscope (SEM) equipment : electronic
gain vs incident energy, gain fluctuations and noise behaviours, pulse height distributions under
multielectron bombardment, and image homogeneity. In SEM, at 20 keV and at room temperature,
the signal to noise is so high that it is possible to count up to 6 electrons in a single pixel. Thanks
to the realization of stable tube prototypes, we have Used such a device in a photocounting astronomical
experiment.
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Sun Angle Sensors are components of satellite attitude control
systems. Here we will discuss the design, fabrication, testing and
performance of a 2 axis sensor with .001° resolution over a
field of view.
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Scanning laser beam semiconductor panel can be used for conversion of millimeter
waves to visual displays. For this easy and direct method of conversion, the behavior
of semiconductor panel under scanning laser beam is required. Formulas for excess
carriers due to moving spot of light have beam obtained. Using these formulas single
path total field attenuation through semiconductor panel for scanning laser light spot
excitation as a function of scanning velocity, position and laser beam width are studied.
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Reflectivity of cascaded gratings with phase-shifts is studied. It is shown that
this structure has wavelength tunability. The effects of phase shift, length of different
stages of the gratings, total length of grating for two and three cascaded grating
stages on tunability are studied in this paper.
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In this paper a general theory for a class of phase retrieval problems of two dimensional
band limitted objects has been developed. A modified form of polynomial di-
1Tision algorithm is used to solve problem.
A new algorithms for latent reference point problem is considered and its
extension to cases in which reference point can move in object plane is also considered.
In order to do this shear interfernnetric method is used. A new algorithm for
sloving the problem with rectangular object has also been developed.
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