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This paper investigates some prerequisites for vessel imaging based on diffuse reflectance measurements in order to develop an optical non-invasive method for the imaging and monitoring of vessels. The method utilizes near-infrared (NIR) radiation (890 nm) from a light emitting diode. The light is guided into the tissue via an optical fibre (diameter 1.0 mm). The backscattered light is collected by an optical fibre of the same type and detected by an optical power meter. The fibres are moved over the skin in two directions with the aid of two motors operated by a microcomputer. Spatially resolved reflectance at the skin surface could be presented as a vessel-map in a colour-coded form on a computer screen. Experimental results indicate that the vessel imaging facility depends upon source-detector separation, relative position and vessel depth, and does not depend essentially on the radiant power from the light source. It is shown that, by a proper choice of probe parameters, one can improve the vessel identification ability. After vessel imaging the technique can potentially be used to monitor several physiological parameters on a selected vascular bed or to distinguish between injured and healthy tissue by monitoring local blood flow, oxygen saturation and the recirculation, pre- and post-operatively.

We propose a no el technique to characterize an electrically tunable liquid-crystal Fabry]Perot interferometer. Only one usual set of a monochromatic light source and an optical power meter is needed. Various characteristic parameters were estimated based on the equi alent refracti e index analysis and the measured oltage-dependent transmittance. Q 1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 48]51, 1999.

When most organic insulators are exposed to thermal stress, they turn darker in color. The increase of electronic transition absorption due to thermal oxidation of the resin is responsible for this darker coloration. A correlation between the degree of aging of these insulators and their reflective absorbances in the near IR (infrared) wavelength range has been established previously. In this paper, a novel non-destructive diagnostic apparatus using an optical fiber sensor developed to evaluate the aging of thermally deteriorated insulators is reported. The key point of this technique is measuring the change of reflective absorbance ratio at two different wavelengths. The sensor consists of two plastic optical fibers (for light transmitting and receiving), a plastic optical coupler, two kinds of near-IR light emitting diodes as light sources, and an optical power meter as a detector, and hence is very compact and lightweight (

A 32-channel 50 GHz spaced arrayed-waveguide grating(AWG) with our innovative configuration has been designed and fabricated. The performance of the device has been fully tested by using a system that consists of a tunable laser light source (TLS), an optical power meter and a polarization controller. The insertion loss (IS) of the device is 4.2–7.4 dB. The crosstalk is about −28 dB. TheIS uniformity is less than 3.3 dB. With our configuration, the performance of the device has been enhanced effectively and the difficulty in alignment process has been decreased obviously.

Degree of polarization (DOP) is an important physical quantity for describing the optical polarization effect and is widely applied in optical fiber communication, optical fiber gyro and the related technologies. Currently, the optical polarization degree tester for the purpose of communication uses mainly two kinds of measurement methods: Stokes vector method and extremum method. At present, there isn’t a standard to measure the accuracy and consistency of DOP parameter measurement by the devices listed above, affecting seriously the application of DOP parameter measurement in the fields of optical fiber gyro and optical fiber communication. So, it is urgent to table the accurate guarantees to trace the source of quantitative values of the DOP measuring devices and testers. In this paper, the polarization beam combination method is raised to research and manufacture the standard optical fiber light source device with the variable DOP, and an indicated error measurement has been conducted for a DOP meter. A kind of standard optical fiber light source device that uses a single light source to realize the variable DOP is put forward. It is used to provide the accurate and variable optical fiber polarization degree light with a scope of 0～100%. It is used to calibrate the DOP meters and widely applied in the field of national defense and optical communication fields. By using the standard optical power meter, DOP value by which the optical power meter calculates the optical signal can be measured, which will be used ultimately for calibration of the DOP meter. A measurement uncertainty of 0.5% is obtained using the polarization beam combination method.

The modern radio-frequency power meters used to realize the power primary standards are based on bolometric detectors direct-current biased by means of a self-balancing current loop. We have updated the electronic components of a self balancing circuit originally developed by NIST and evaluated its performance in the terms of Noise Equivalent Power. The performed measurements give NEP = 1.5 × 10 −10 W/√Hz for the whole power meter and a NEP Electronic = 1.2 × 10 −10 W/√Hz for the electronic component at a temperature of 296 K.

During the macrobending loss performance tests of ITU-T G.657 fiber under small bending radius, the test results show big differencesin many tests for the same test samples and conditions. Research shows that the main reason for the difference is Whispering gallery modes phenomenon in small bending radius [1]. The inappropriate test conditions can affect the accuracy of macrobending loss test results. In the test of product validation and field application, single wavelength light source and optical power meter were often used. How to judge whether there is effect existing and how to remove the Whispering gallery modes influence in the testing process has become the key to correctly test macrobending loss by light source and optical power meter. This paper introduces the method of eliminating Whispering gallery modes effect during the macrobending test under small bending radius by single wavelength light source and optical power meter.

We propose a highly sensitive curvature sensor based on cascaded single mode fiber (SMF) tapers with a microcavity. The microcavity is created by splicing a small piece of hollow core photonic crystal fiber (HCPCF) at the end of an SMF to obtain a sharp interference pattern. Experimental results show that two SMF tapers enhance the curvature sensitivity of the system and by changing the tapering parameters of the second taper, the curvature sensitivity of the system can be tailored, together with the fringe contrast of the interference pattern. A maximum curvature sensitivity of 10.4 dB/m−1 is observed in the curvature range 0 to 1 m−1 for a second taper diameter of 18 μm. The sensing setup is highly stable and shows very low temperature sensitivity. As the interrogation is intensity based, a low cost optical power meter can be utilized to determine the curvature.

Optical fibreless data networks P2P offer fast data transmissions with big transmittance from 1- 10 Gbps on a distance of 1- 6 km. Perfections of such networks are especially flexibility, rapid creation of communications. Sensitivity to atmospheric influences, necessity of light on sight belongs to disadvantages. Transmission through atmosphere be characterized by non-stationarity, inhomogeneity, the influences have random character. It means immediately that it is possible only with difficulty to project conclusions concerning to the measurement on one line upon fiberless line in another position. Contribution tackles a question of forming of the artificial hazy atmospheres, finding the statistical parameters of artificially created foggy atmospheres that could be reproduced to real environment. This work describes created laboratory apparatus powered with fog generator, heat source and ventilating fans, which allow in a controlled way to change the optical transmission inside the bounded space. Laser diode radiation at wavelength of 850 nm is transmitted into created space like this which is scanned with optical power meter after passing of artificially created turbulent vaporous environment. Changes in intensity of the passed lights are captured; the mean value and maximum deviation from the mean value are computed. In this way it is possible to change the reached specific attenuation in dB/km. Owing to turbulences it happens to deviations from the mean value, these abnormalities are characterized by the distribution function that describes the size of turbulences in time. By the help of ergodic theorem then it is possible to deduce that the distribution function of the foggy turbulences gained at continuous time evaluation has same history like the distribution function gained behind the same conditions in the setup in other times. It holds as well that these distribution functions are the same for variety of points in experimental space, provided there are well - kept the same conditions of turbulence creations. Contribution shows the experimental values, shapes of distribution functions, their influence on attenuation of fiberless communication lines and on achieved the transmission BER. At the present time the verification of conclusions is performed from the experimental model on outdoor connecting link working upon the distance of 1,3 km at the transmission rate of 1,25 Gbps.

A wide-area sensor network based on fiber optic power supply is reviewed. This sensor network is composed of hundreds of sensor nodes driven by the laser power. Each sensor node produces optical signals by modulating a part of the supplied laser light and sends these signals to a monitoring station. The optical power required for driving one sensor node is less than 2 mW. Because each sensor node can control two or three sensors, a single laser diode with 1 W is sufficient for driving 1,000 sensors. The proposed sensor network can also be integrated with wireless sensors, which enables ubiquitous sensing.

This is a copy of an article published in the Photomedicine and Laser Surgery © 2012 copyright Mary Ann Liebert, Inc.; Photomedicine and Laser Surgery is available online at: http://online.liebertpub.com Objective: The purpose of this study was to investigate the rat skin penetration abilities of two commercially available low-level laser therapy (LLLT) devices during 150 sec of irradiation. Background data: Effective LLLT irradiation typically lasts from 20 sec up to a few minutes, but the LLLT time-profiles for skin penetration of light energy have not yet been investigated. Materials and methods: Sixty-two skin flaps overlaying rat’s gastrocnemius muscles were harvested and immediately irradiated with LLLT devices. Irradiation was performed either with a 810 nm, 200mW continuous wave laser, or with a 904 nm, 60mW superpulsed laser, and the amount of penetrating light energy was measured by an optical power meter and registered at seven time points (range, 1–150 sec). Results: With the continuous wave 810nm laser probe in skin contact, the amount of penetrating light energy was stable at *20% (SEM – 0.6) of the initial optical output during 150 sec irradiation. However, irradiation with the superpulsed 904 nm, 60mW laser showed a linear increase in penetrating energy from 38% (SEM – 1.4) to 58% (SEM – 3.5) during 150 sec of exposure. The skin penetration abilities were significantly different ( p < 0.01) between the two lasers at all measured time points. Conclusions: LLLT irradiation through rat skin leaves sufficient subdermal light energy to influence pathological processes and tissue repair. The finding that superpulsed 904nm LLLT light energy penetrates 2–3 easier through the rat skin barrier than 810nm continuous wave LLLT, corresponds well with results of LLLT dose analyses in systematic reviews of LLLT in musculoskeletal disorders. This may explain why the differentiation between these laser types has been needed in the clinical dosage recommendations of World Association for Laser Therapy. publishedVersion

This study conducted computations and experiments to demonstrate the relationship between areas of reflection spectra and strain gradient chirps along a fiber grating. Previous studies have shown that strain gradient chirps on an FGB lead to distortions on its reflection spectrum. However, in applications, how to use a practical measurand (obtained directly from an FBG) to deduce the strain gradient chirp has seldom been addressed in previous studies. The current literature have found that the bandwidth and area of a spectrum are two possible parameters to deduce the strain gradient. From an economic and technological perspective, even in the dynamic measurements, the areas of reflection spectra can be measured by an optical power meter. In this article, based on the coupled-mode theory, a series of computations were performed to obtain the calculated relationship. To validate the calculated relationship, related experiments were also conducted. This relationship is not mentioned in the current literature, numerically and experimentally.

With the development of science and technology, and enlargement of the field of application, the requirements for measuring range of laser meter become more and more critical. To solve the problem that short-range measurement capability of certain model of laser meter is limited, the method of defocusing, translation APD and setting the reflector to enhanced the effective detection energy and improve signal-to-noise ratio (SNR) of the short-distance measurement is presented. Meanwhile, based on the optical design, present system alignment method and assembly tolerances, and the computer simulation was conducted, Results proved that short-distance measurement capability of laser meter is effectively enhanced.

Polished Single Mode Fiber (SMF) has been used to develop an evanescent wave sensor whose response varies in presence of Volatile Organic Compounds (VOCs). A vapochromic complex has been fixed along the polished section following the Layer-by-Layer method (LbL). The sensor was studied in a transmission configuration, using a laser @ 1550 nm as light source and an optical power meter as receptor. The temporal response was registered for different organic vapors, observing distinct dynamic ranges and recovery times: both can be used to discriminate between the VOCs.

In case of teaching optical system construction, it is difficult to prepare the optical components for the attendance student. However the tangible learning is very important to master the optical system construction. It helps learners understand easily to use an inexpensive learning system that provides optical experiments experiences. Therefore, we propose the new education system for construction of optical setup with the augmented reality. To use the augmented reality, the proposed system can simulate the optical system construction by the direct hand control. Also, this system only requires an inexpensive web camera, printed makers and a personal computer. Since this system does not require the darkroom and the expensive optical equipments, the learners can study anytime, anywhere when they want to do. In this paper, we developed the system that can teach the optical system construction of the Denisyuk hologram and 2-step transmission type hologram. For the tangible learning and the easy understanding, the proposed system displays the CG objects of the optical components on the markers which are controlled by the learner's hands. The proposed system does not only display the CG object, but also display the light beam which is controlled by the optical components. To display the light beam that is hard to be seen directly, the learners can confirm about what is happening by the own manipulation. For the construction of optical holography setup, we arrange a laser, mirrors, a PBS (polarizing beam splitter), lenses, a polarizer, half-wave plates, spatial filters, an optical power meter and a recording plate. After the construction, proposed system can check optical setup correctly. In comparison with the learners who only read a book, the learners who use the system can construct the optical holography setup more quickly and correctly.

A novel load sensor has been proposed and demonstrated by embedding a fiber Bragg grating (FBG) into a tapered cylindrical polymer rod. Load-induced nonuniform strain field changes the bandwidth, and hence, the reflected optical power of the FBG. Temperature-insensitive measurement of load has been realized by measuring the reflected optical power with only a low-cost optical power meter. Load measurement sensitivity of 5.0 nW/N has been experimentally achieved within a range up to 1800 N. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:930–933, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26695

CESNET is an association of universities and Academy of science of Czech Republic. It is operating a national research and education network (NREN) interconnecting all university cities in the republic. So called CEF - customer empowered fiber - is used on lot of CESNET backbone lines. In this paper we discus CESNET developed technology used to enlight leased dark fiber lines. We especially concentrate on the newly developed SNMP based power meter.

To test the parameters of image intensifier screen is the precondition for researching and developing the third generation image intensifier. The picture of brightness uniformity of tested fluorescence screen shows bright in middle and dark at edge. It is not so direct to evaluate the performance of fluorescence screen. We analyze the energy and density distribution of the electrons, After correction, the image in computer is very uniform. So the uniformity of fluorescence screen brightness can be judged directly. It also shows the correction method is reasonable and close to ideal image. When the uniformity of image intensifier fluorescence screen brightness is corrected, the testing instrument is developed. In a vacuum environment of better than 1×10-4Pa, area source electron gun emits electrons. Going through the electric field to be accelerated, the high speed electrons bombard the screen and the screen luminize. By using testing equipment such as imaging luminance meter, fast storage photometer, optical power meter, current meter and photosensitive detectors, the screen brightness, the uniformity, light-emitting efficiency and afterglow can be tested respectively. System performance are explained. Testing method is established; Test results are given.

This paper demonstrate novel coupler 1 × N coupler based on polymer optical fiber (POF) was fabricated by handwork fusion method using yellow flame burner and metal tube. A new additional process - twisting-effect removal - is demonstrated to enhance fusion quality. For the purpose of performance characterization, LED fiber source with 650 wavelengths was injected into input fiber while optical power in output fibers was measured by optical power meter. The final results showed that the power-splitting performance of the coupler is satisfying since the insertion loss and excess loss is extremely low (< 7 dB and 0.53 dB, respectively). For video surveillance application, the coupler has potential for high quality video transmission in tree-topology communication system.

We present a method of optical power measurement which can be used to measure optical radiation over a large part of the optical spectrum without switching between different sensor types. Based on resonant optothermal detection using a miniature quartz tuning fork, we find that the use of this method has superior dynamic range in the measurement of optical power. With use of the pyroelectric effect, sensitivities are comparable to standard pyroelectric detectors and measurement of quasi-CW modulated optical signals is a simple task. An optical power meter which uses this method can be put to use as a compact and low cost device in a wide variety of applications.

A fiber loop mirror (FLM) temperature sensor using a long-period grating (LPG) written in a photonic crystal fiber (PCF) and a band-pass filter as a demodulator is proposed. By utilizing the stable filtering function of the LPG in the PCF, the resonant wavelength variation of the FLM with temperature is transferred effectively to the intensity variation of the output light. By monitoring the light intensity of the band-pass of the filter, temperature applied on the FLM is deduced by an optical power meter. Experiment results show that the temperature sensitivity is high as ~1.742 dB/ °C when a filter with a full width at half maximum 3 nm and the center at 1545 nm is used.

We demonstrate a wide-area fiber sensor network composed of sensor nodes driven by the power of transmitted laser light. The sensor node produces optical signals by modulating a part of the laser light and sends it back to the monitor. The developed sensor node was driven with an input optical power of 1.7 mW. The number of the sensor nodes is also discussed theoretically. It is clarified that more than 1,000 sensor nodes can be placed along an optical fiber line by using a high-power laser diode of 1 W.

We present a novel inspection technique for cleaved optical fiber ends based on the Fabry-Perot resonator. The technique uses mainly laser diodes, an optical power meter, 3-dB coupler, and XY lateral adjustment stage. It can be achieved more easily than current imaging processing that uses a charge coupled device camera and video monitor. The inspected fiber end is considered failed or successful depending on whether both the measured return losses from the fiber end at two wavelengths are equal to ~14.7 dB. Experimentally obtained fiber end images were in good agreement with scanning electron microscope observation images. Thus, the proposed technique provides a simple and cost-effective way to inspect cleaved optical fiber ends.

Lasers diodes convert electrical power to a highly collimated beam of Optical power that may propagate over meters with insignificant losses. At the the other end of this optical link Photovoltaic diodes may be used to retrieve electrical power. This point-to-point wireless power transmission is safe if all the optical power is accounted for using an information feedback from the receiver. In addition, safety can also be guaranteed by monitoring the periphery of the optical beam. Optical fields at long wavelengths > 1400nm have lower absorption losses and have higher threshold power density (P optical (W) over m2) for human safety. We present various technological challenges in the design and preliminary experimental results of such a system which may be integrated into compact packages.

This paper proposed a method which utilizes phase-matched FWM to effectively enhance the chromatic dispersion (CD) monitoring sensitivity and monitoring range of the signals with high duty cycles. The scheme was realized by inputting a signal and continuous probe wave simultaneously into high nonlinear fiber, and the generated idler wave, whose power carried the CD information, was followed by a filter and optical power meter. The numerical simulation showed clearly that through employing this method, the monitoring range for CSRZ and NRZ could be 8 and 6.2dB respectively. In this paper we also puted forward a peak search algorithm utilizing a TDC module to increase NRZ and CSRZ monitoring range to 800 ps/nm. (3 pages)

We summarize various sensors based on photonic crystal fiber loop mirrors proposed by our research team, including strain sensors, temperature sensors and curvature sensors. Both of highly birefringent and lowly birefringent photonic crystal fibers (PCFs) have been inserted into fiber loop mirrors (FLMs) as the sensing elements. A temperature-insensitive strain sensor with highly birefringent PCF based FLM has been realized and it has a strain sensitivity of 0.23 pm/µe in the range of 0–30 me. For a low-cost, a demodulation is proposed by using a distributed-feedback (DFB) laser as the light source and an optical power meter instead of an expensive OSA. Strain and curvature sensors based on FLMs are also demonstrated by using a lowly birefringent PCF, which has a strain sensitivity of 0.457 pm/µe and a curvature sensitivity of 0.337 nm/ m −1 , respectively. Further, a novel and compact temperature sensor based on a FLM combined with an alcohol-filled highly birefringent PCF is proposed and experimentally demonstrated and it has a high sensitivity as high as 6.6 nm/°C.

A plastic scintillating fiber consisting of a doped polystyrene core and a cladding of poly(methyl methacrylate) was found to detect γ-rays at dose rates of above 5 mR/h by a photoncounting module and above 20 mR/h by an optical power meter

A calorimeter for optical fiber power measurement is developed. It has a compensative absorber to stabilize environmental disturbance, and two types of adapters for optical fibers and light beams. The uncertainty in measurements of 1-mW and 10- mu W optical fiber power was evaluated as +or-0.18% and +or-0.45% respectively, expressed as two standard deviations. The calibration uncertainty of an optical fiber power meter using the calorimeter as a primary standard is reduced by more than one half compared to that of the conventional method using a laser beam calorimeter and photodiode-type transfer standard. >

The paper presents a method for the attenuation measurement of the optical path from ONU to OLT in GPON network. Optical power meter is connected to the fiber section via splitter in central office receiving optical signal from all ONU's. Optical power difference is measured in upstream signal with desired ONU in “on” or “off” state. The difference has a linear relationship with user's bandwidth. Finally paper describes an experimental setup for confirmation of proposal, the results differ by 2,5% from theoretically calculated. The system will improve the service reliability and reduce the maintenance cost.

Based on Michelson interferometer principle and controlled via an elaborately designed computer program, the variation of interference order, which contains the information of refractive index and its variation, can be detected by an optical power meter and a CCD camera. According to the relation between the increment of interference order and the change in optical path difference, the refractive index of photopolymer samples can be calculated in an accurate way. Typical measurements of the refractive index of our photopolymer samples are 1.547 and 1.583 at wavelength 532nm and 457 nm, respectively.

A practical sensor with high sensitivity for the temperature measurement by using a highly birefringent (HiBi) fiber loop mirror (FLM) concatenated with a long-period grating (LPG) written in a photonic crystal fiber (PCF) is proposed. Only HiBi-FLM acts as a sensor head, while the PCF-LPG serves as a temperature insensitive filter to provide wavelength dependent optical power transmission. A bandpass filter is used to provide a narrow band light source, thus only one of transmission peaks of the HiBi-FLM is located within a negative linear region of the LPG's transmission spectrum. By utilizing the stable filtering function of the PCF-LPG, the resonant wavelength variation of the FLM with temperature is transferred effectively to the intensity variation of the output light. The temperature applied on the FLM is deduced by a cheap optical power. As a result, the sensitivity of the sensor is about -0.4872 dB/°C. When an optical power meter with the resolution of 0.01 dB, a temperature resolution of 0.02°C is achieved.

This paper presents the simplest and fastest technique on testing and troubleshooting a passive optical network (PON) using handheld optical power meter and optical time domain reflectometer (OTDR). This provides a faster, simpler, and less complex way for installation testing, service activation testing, and network performance monitoring and troubleshooting a PON network without need of optical spectrum analyzer (OSA). The architecture is divided into 2 parts; electronic application injection and optical layer. Two units of handheld optical power meters is used as the injected wavelength and measurement meter for the triple-play (data, voice, and video) services. The whole network status line-to-line connection could be troubleshot with OTDR for further processing. Finally, we proposed the automatic monitoring network scanning to define the status of network by using our developed program by means of Smart Access Network Testing Analyzing and Database (SANTAD). A very simple set up and visual basic programming enable all status lines can be displayed and monitored onto one computer screen by means of Centralized Failure Troubleshooting System (CFTS).

We describe a fiber optic voltage sensor with optically controlled sensitivity. The sensor operates at two widely separated wavelengths (633 and 976 nm), one of which is a control signal (976 nm). We show that at a properly chosen wavelength of the control signal and of the phase-retarding element, variations of the power of the control signal allow increases or decreases in the sensitivity of the sensor. A theoretical analysis of sensitivity as a function of the optical power of a control signal is presented. We have demonstrated experimentally variation of the sensor's sensitivity from 0.01% to 0 per 1 V/sub rms/ of control power changes in the range of 0-7 /spl mu/W.

We propose and experimentally investigate a highly reliable WDM-PON system. The proposed system adopts the colorless solution. It can detect the failure of the feeder fiber by the polling and restoring mechanism of the system management module, and then trigger the OSW switching to the preplanned path for restoring the disrupted traffic, and produce a broken fiber alarm if needed. The system management module can send polling frames to ONUs periodically and judge whether it is necessary to send trigger signals to the OSW according to the number of ONUs registered in line cards. The preplanned path is the feeder fiber of the neighboring line card. This system can automatically protect against the feeder fiber failures without duplicating the feeder fiber link. The OTDR or optical power meter can be saved which is used for on-line monitoring. Its restoration time is less than 16ms in experiments.

The objective of this study is to determine and troubleshoot the problems of using handheld optical power meter and optical time domain reflectometer (OTDR) for monitoring and troubleshooting a conventional passive optical network (PON) equipped with optical splitter/coupler that used to broadcast optical signals from one fiber to many fibers. This paper proposes an appreciate approach to overcome these testing challenges. In this enhancement, a commercially available OTDR is located at central office (CO) and a tapper circuit is designed to allow the OTDR testing signal to bypass the optical splitter/coupler in a conventional PON when emitted from CO towards customer sites for centralized monitoring in downstream direction. This provides a faster, simpler, and less complex way for installation testing, service activation testing, and network performance monitoring and in-service troubleshooting a PON.

A scattering measurement system to determine the optical characteristics of industrial suspensions in the wavelength range 430-700 nm was realized. The suspensions were mixtures of water and solid matter; the optical characteristics measured were the absorption coefficient, the scattering coefficient and the anisotropy. The measurement system comprised two integrating spheres of 203 mm diameter, a light source and a multichannel optical power meter. Different lasers and a halogen lamp were used as light sources. Optical power was measured with a spectrophotometer or a conventional power meter.

We report here the development of an automated modern optics laboratory for undergraduate students. This developed modern optics laboratory have automated experiments on optoelectronic device characterisation, optical instrumentation, CCD based optical experiments and advanced applications in optics. In the device characterisation section, Voltage-Current (V-I) and Optical Power-Current (P-I) characteristics of various optoelectronic devices like LEDs, Laser diodes and photo diodes have been automated. In the optical instrumentation section, development of PC based optical power meter have been reported whose functionality can be tailored as per the need of the designed experiment. In the CCD based optical experiments section, CCD has been integrated for fringe capture and analysis by studying the diffraction pattern of a pinhole. In the advanced applications in optics section, molar absorbivity of NiSO4 has been calculated. Further work is in progress to develop heart rate monitoring system, non-evasive jaundice studies from the skin, CCD based real time spectrometers as well as elaborate studies on interference, diffraction and polarisation. The automation of this laboratory has been done by integrating various sensors (photodetectors, CCDs, Current and others) with data acquisition cards connected to PC and one of the most widely used world wide scientific graphical programming software LabVIEW. The purpose of the laboratory is to invoke student interest by exposing them to various modern tools in comparison to very conventional as well as boring existing optics laboratories. The use of this scientific graphical programming software will help in performing various real time measurements and calculations with ease. The automation of the experiments will also save great amount of experimentation time and procurement of costly equipments dedicated to each experiment thus providing an efficient way to carry out studies with reduced financial constraints and better manoeuvrability.

A novel monolithic power meter has been developed for submillimeter-wave applications (100 GHz to 10 THz). The detector is a large-area bismuth bolometer integrated on a 1.2- mu m-thick dielectric membrane. This approach results in a wide-band, high-responsivity detector. The power meter is simple to fabricate, is inexpensive, and can be easily calibrated using a low-frequency network. Quasi-optical measurements at 90, 140, and 240 GHz show that the bolometer is polarization-independent and could be modeled by a simple transmission line model. Absolute power measurements at 90, 140, and 240 GHz show a +or-5% accuracy and agree well with a calibration Anritsu power meter at 90 GHz. Potential application areas are power calibration, antenna coupling efficiency measurements, and absolute power measurements from solid-state devices and far-infrared lasers at submillimeter wavelengths. Absolute output power measurements on a 220-280 GHz tripler using the quasi-optical power meter are presented as an application example. >

A high-precision linearity standard for high-power optical fiber power meters (OFPMs) at 1550 nm is developed using an integrating sphere and an InGaAs photodiode connected to a picoammeter. Its linearity is evaluated in the superposition method, where optical signals are superposed in the integrating sphere using a two-core ferrule to avoid high loss and high-power instability of an otherwise used fiber coupler. The uncertainty (k=1) of this standard's linearity at 1 W with reference power 1 mW is less than 0.002 dB. Test OFPMs' linearity is calibrated by comparison with this standard within an extended uncertainty (k=2) of 0.005 dB at 1 W.

Stroboscopic scanning white light interferometry is a method for dynamic nanometer range profilometry that is widely applied for quality control in the MEMS industry. Monochromatic and phosphor coated (PC) white LEDs produce short light pulses for stroboscopy. The time resolution of a stroboscopic setup depends on its capability to produce short light pulses with duty cycles less than 5%. The peak wavelength and the spectral shape of PC white light diodes change with duty cycle. The spectrum of a PC white light LED was measured using Czerny-Turner-type monochromator (Jobin Yvon H 25) with an optical power meter (Ando AQ-1125). A custom made pulse amplifier drove the LED with a square wave voltage at 120 Hz. The blue peak wavelength of the white diode was blue-shifted by 7 nm when the duty cycle was reduced from 10% to 0.5%. The impact of the spectral change on the vertical resolution of the stroboscopic measurement was characterized through simulating the change in measurement uncertainty. The results were applied to characterize out-of-plane vibration of thermal MEMS bridges manufactured from SOI wafers. The simulated increase in measurement uncertainty was 1 nm, when the spectrum shifted 10 nm towards blue. Noise from background vibration obscured the effect of spectral shift. Although literature says that temperature increase shifts the spectrum of LED, and although our simulations indicate the existence of such a shift, our experimental results indicate that the deletory effect is negligible (it does not introduce bias or uncertainty to profiling measurement).

We report an intensity based fiber strain sensor using a long period grating (LPG) pair along with an in-line core mode blocker. By sandwiching the core mode blocker fabricated by arc method between a LPG pair, an band-pass filter was formed. Measured by optical power meter at one specific wavelength, the transmitted power was found to decrease as a variation of axial strain is applied on one single LPFG, therefore we can measure the applied strain by measuring the transmitted power. The measured response of voltage for change of strain was 6.37pV/ μe.

This work discusses the measurement principle of fiber Bragg gratings (FBGs). Aim of the work is found a cheap method for measuring grating reflectivity and implement it into education. This principle takes advantage of laser diode wavelength dependence on temperature. Then FBG reflectivity can be measured by common laser diode and optical power meter without using expensive optical spectrum analyzer and broadband light source.

As the testing requirements for 3G communication installations and CDMA networks come closer, the need for making peak or pulse power measurements grows faster and more important. The CW power sensor can be measured and characterized by the national standards laboratories. Therefore, it is the most accurate measurement parameters in the microwave power fields. For the convenience of inspecting the performance of the peak power sensor with its meter at the users' end, we have constructed a serial of functional tests, which are based on the CW power sensor standards. In this paper, the author discusses each measurement method and its tolerance, with limitations. At the same time, there is a comparison of the test methods that are provided by other manufacturers.

Planar lightwave circuit (PLC) chips based on III-V semiconductor MQW rib waveguide promise to be not only a solution to information access, but also direct the issues of bandwidth, pin count, reliability and complexity. Nanopositioning and precision alignment addresses vital importance in high-efficient connectivity between PLC chips and fiber arrays. Refractive-index mismatching between fused silica and III-V compound is one of the most serious problem which remains unsolved on one hand as well as mode field mismatching which can be mitigated in other hand through gradient geometry structure such as tapered spot size converter (SSC) and specialty fibers such as wedge-shaped fiber (WSF). Spherical gradient refractive-index (SGRIN) media intervened between WSF and MQW rib waveguide is put forward. The GRIN media virtually eliminates the reflection losses associated with the fused silica-air interface and III-V semiconductor-air interface. The beam spot emitted from WSF are observed by digital camera and the fundamental mode of MQW rib waveguide was calculated out. Lightwave propagation and mode field evolution in the WSF-SGRIN-PLC system is simulated by FDTD method with the coupling loss of 8.54dB at a wavelength of 1.55μm. An LED signal is injected into WSF, transmitted along GRIN media and PLC waveguide and output through single mode fiber (SMF). Optical power meter-based measurement verifies the whole system coupling loss to be consistent with the numeric estimation. The approach provides an experimental prototype for coupling and packaging technique of integrated photonic devices, hence supplying foundation for photonic network.

Optical fiber alignment devices are highly necessary in optical communications. In this paper, we developed a micromanipulation robot for automatically performing optical fiber alignment task. The system consists of a precision parallel robot with 6 D.O.Fs, a nano positioning stage with 5 D.O.Fs, two microscopes, two CCD cameras, an optical power meter and a fusion device. Directed by the micro-vision system, the precision parallel robot can realize fiber alignment with 0.5 /spl mu/m resolution and 2 /spl mu/m repetitive accuracy. The nano positioning stage is actuated by piezoelectric and 10 nm resolution can be gained. Under the help of optical power meter and through optimal searching method, the fiber can be positioned precisely. With this system, a single mode optical fiber alignment task has been finished automatically. The average splice loss is about 0.016dB. The system can also realize the alignment of fiber and optical devices for its multi DOFs. It will play a key role in the field of optical engineering.

We describe a calibration system that measures the nonlinearity of optical fiber power meters (OFPMs) at a maximum power of 0.6 W and a minimum power of 0.2 mW at 1480 nm. The system is based on the triplet superposition method. This system measures the nonlinearity of OFPMs by using correction factors at different powers; the system is an important tool for characterizing OFPMs at high powers in the S band. The measurement uncertainties, typically better than 0.2%, k = 2, associated with the high-power nonlinearity system are also described.

A burst-length-setting and phase-optimization technique were proposed for use in QKD, and we demonstrated their repeatability. QKD could automatically be installed on a strange optical line with these techniques.

Fiber voltage sensors based on the electro-optic effect are described. The basis of sensor operation and the effect of sensor design parameters on system performance are described. Field test and laboratory test results are presented from fiber optic voltage sensors collected at the US Army ETDL's Pulsed Power Center and Sandia National Laborato ries.