谐振式空心光子带隙光纤陀螺中的光克尔效应

谐振式光纤陀螺(PROG)采用空心光子带隙(HCPBG)光纤后,光克尔效应引入的系统漂移将会与普通单模光纤(SMF)谐振式陀螺系统中的有所不同。为了研究谐振式空心光子带隙光纤陀螺中光克尔效应的变化情况,采用光场叠加的方法,从理论上分析谐振式空心光子带隙光纤陀螺中的光克尔效应,同时针对光克尔效应引入的系统漂移进行了数值仿真,并且与普通单模光纤谐振腔陀螺中的光克尔效应进行对比。理论计算表明,采用空心光子带隙光纤的谐振式光纤陀螺比采用普通单模光纤谐振式陀螺的光克尔效应有明显的降低,在光源线宽不变时,不同光纤环长度对应的光克尔效应引起的旋转角速度漂移前者比后者降低了1~2个数量级。     

Analysis on state of polarization of stimulated Brillouinscattering in an optical fiber ring-resonator

As a basic study of a Brillouin fiber-optic gyro, the state of polarization of stimulated Brillouin scattering in an optical fiber ring-resonator is analyzed. A high-birefringent fiber ring-resonator with 90° polarization axis rotation at the splice is considered as a candidate to have a stable lasing. It has two special states of polarization as the lasing modes, namely the polarization lateral modes. The lasing frequencies, namely the longitudinal modes for one state are fixed just in the middle point between the two neighboring lasing frequencies for the other in this resonator. This means that the stable single mode lasing may be obtained. The lasing threshold, the alternation of the lasing modes are discussed both by the simplified theory and the strict theory     

Resonance characteristics of backscattering in optical passive ring-resonator gyro

Resonance characteristics of the backscattering in an optical passive ring-resonator gyro (OPRG) are observed. This resonance has two peaks with a separation equal to the Sagnac phase shift when rotation is induced. The experimental results are in good agreement with the theory that we have already presented. This phenomenon degrades the gyro linearity in a configuration to obtain the frequency output.     

Ring-resonator method - effective procedure for investigation of microstrip line

In addition to the traditional application of the ring-resonator method for determination of the microstrip line effective permittivity, measurements of the insertion losses and equivalent substrate permittivity are proposed. The obtained data for a number of isotropic and anisotropic substrate materials are in good agreement with the results predicted theoretically.     

Si Photonics and Fiber to the Home

This paper describes Si photonics and the key application to fiber-to-the-home (FTTH). Mass production in terms of complementary metal-oxide-semiconductor technology is a prerequisite for Si photonics to provide a cost-effective solution, and FTTH should meet this requirement. We describe a design of the FTTH chip architecture with wavelength-division multiplexing based on ring-resonator demultiplexers and multiplexers. The grand challenge of Si photonics for this application is the production of Ge photodetectors and modulators.     

Differential Polarization Delay in Coupled-Resonator Optical Waveguides

An integrated device capable of dynamically controlling the differential delay between two orthogonally polarized data channels is presented. The polarization-selective delay is induced by exploiting waveguide birefringence in a ring-resonator coupled resonator optical waveguide. A prototype realized in silicon-oxynitride technology is employed to manage the differential delay between two polarization-division-multiplexed channels modulated up to 10 Gb/s over several bit-slots. Reconfiguration is achieved by thermo-optic effect with 1-ps delay accuracy. Back-to-back and propagated bit-error-rate measurements show minor deterioration of the signal with negligible polarization crosstalk.     

Optical Ring-Resonator Random-Access Memories

This paper examines the properties of optical resonator memory cells, in which a data bit is stored in a high- optical resonator. It is shown that resonator-based optical memories are ultimately limited by losses in the resonators, by the extinction ratio and chirp of the variable coupling medium that injects and extracts data into and out of the resonators, and by chirp on the input signal. Using a simple analytical model and accurate field-based simulations, we analyze the performance of a ring-resonator optical memory cell and compare this with the performance of slow light delay line buffer memories and complementary metal-oxide-semiconductor embedded dynamic random-access memory.     

A comparison of the radiation vulnerabilities of ring resonator andinterferometric fiber optic gyroscopes

A comparison is made between passive ring-resonator and interferometric fiber-optic gyroscope sensitivity to the radiation darkening of optical fibers. The radiation degradation factor for each type of gyroscope is developed, and figures of merit are given for comparing gyroscopes independently of the specific mechanization or modulation scheme used. It is shown that for most practical situations, interferometric gyros offer superior performance in radiation environments     

Polarization converters based on ring-resonator phase-shifters

In this letter, novel devices based on ring-resonator phase-shifters are proposed for the realization of efficient polarization converters with periodical spectral response. The main spectral properties of several architectures, including parallel-coupled and directly coupled ring-resonators, are analytically investigated and conditions for complete polarization rotation are derived. The exploitation as polarization interleavers and polarization splitters/combiners is also briefly discussed.     

Analysis of fiber Brillouin ring laser composed ofsingle-polarization single-mode fiber

A fiber Brillouin ring laser made of SPSM fiber is analyzed. The eigenstate of polarization (ESOP) is strictly considered both for the pump and the Stokes light. It is clarified that the laser intensity fluctuation caused by the interaction between two kinds of ESOP is highly suppressed in this structure. The numerical computations using the typical values show that the fluctuation within 7.5% can be realized for the output Stokes light. While this ring-resonator does not offer high-grade performance when applied to the passive resonator fiber optic gyro, it could realize the high-grade performance when applied to the Brillouin fiber optic gyro     

Novel fibre optic gyroscope with a configuration combining Sagnac interferometer with fibre ring resonator

A novel fibre optic gyroscope, with a structure making use of the combination of a Sagnac interferometer with an active fibre ring-resonator, is proposed and analysed. The proposed gyroscope can be viewed as a generalised structure of the conventional Sagnac interferometric type fibre optical gyroscope. It has the advantages of both long fibre loop length and multipath interferences. By inserting a fibre amplifier in the loop to provide an optical gain of several dB, the relative maximum sensitivity is enhanced to approximately 30 times more than that of conventional Sagnac interferometric fibre optic gyroscopes.<>     

Bias of an optical passive ring-resonator gyro caused by themisalignment of the polarization axis in the polarization-maintainingfiber resonator

An analysis is presented of the bias of an optical passive ring-resonator gyro caused by the misalignment of the polarization axis in the resonator formed by the polarization-maintaining fiber. A large bias takes place when the phase difference between the two polarization modes of the fiber is equal to the amount of 2π times an integer. It is clarified that the bias can be suppressed by setting the fiber polarizers at the lead portions of the resonator, which was a method proposed originally to reduce the bias in an ideal resonator without the misalignment     

Monolithically integrated resonator microoptic gyro on silicaplanar lightwave circuit

We report a novel configuration of resonator microoptic gyro (MOG), which is monolithically integrated on silica planar lightwave circuit (PLC) with countermeasures for noise factors. Optical ring-resonator gyros suffer mainly from polarization fluctuation induced noise and backscattering induced noise. We discuss eigenstate of polarization in the waveguide to clarify behavior of the former and propose a countermeasure with control of the waveguide birefringence. As for the latter, binary phase shift keying (B-PSK) with a special signal processing is proposed. Thermooptic (TO) phase modulation is the only one scheme to apply B-PSK in the silica waveguide, whose bandwidth is limited to ~1 KHz. To utilize the narrow bandwidth of the TO modulator effectively, we propose an electrical signal processing scheme and a modulation waveform to compensate the frequency response. By constructing an experimental setup, suppression of the backscattering induced noise is demonstrated, and the gyro output is observed with applying an equivalent rotation     

Kerr effect in an optical passive ring-resonator gyro

The Kerr effect in an optical passive ring-resonator gyro (OPRG) is analyzed considering the optical source coherence. This effect causes the drift to be much greater than the theoretical limit of rotation sensing given by the detector shot noise for an OPRG with high sensitivity. The drift depends not only on the fluctuation of the power splitting ratio between two counter-propagating beams in the resonator, but also on the frequency modulation indices used to set the operating point. Square-wave intensity modulation of the incident beam is also discussed as a way to eliminate the drift. It is found that the ratio of the signal-beam round-trip time in the resonator to the modulation period must be an integer to optimize the drift elimination. From the practical viewpoint, the requirement for the modulation parameters is analyzed numerically.     

A Dual-Polarized Planar-Array Antenna for S-Band and X-Band Airborne Applications

A new dual-frequency dual-polarized array antenna for airborne applications is presented in this paper. Two planar arrays with thin substrates (R/T Duroid 5880 substrate, with εr = 2.2 and a thickness of 0.13 mm) are integrated to provide simultaneous operation at S band (3 GHz) and X band (10 GHz). Each 3 GHz antenna element is a large rectangular ring-resonator antenna, and has a 9.5 dBi gain that is about 3 dB higher than the gain of an ordinary ring antenna. The 10 GHz antenna elements are circular patches. They are combined to form the array with a gain of 18.3 dBi, using a series-fed structure to save the space of the feeding line network. The ultra-thin array can be easily placed on an aircraft's fuselage, due to its lightweight and conformal structure. It will be useful for wireless communication, radar, remote sensing, and surveillance applications.     

Fully programmable ring-resonator-based integrated photonic circuit for phase coherent applications

A novel ring-resonator-based integrated photonic chip with ultrafine frequency resolution, providing programmable, stable, and accurate optical-phase control is demonstrated. The ability to manipulate the optical phase of the individual frequency components of a signal is a powerful tool for optical communications, signal processing, and RF photonics applications. As a demonstration of the power of these components, we report their use as programmable spectral-phase encoders (SPEs) and decoders for wavelength-division-multiplexing (WDM)-compatible optical code-division multiple access (OCDMA). Most important for the application here, the high resolution of these ring-resonator circuits makes possible the independent control of the optical phase of the individual tightly spaced frequency lines of a mode-locked laser (MLL). This unique approach allows us to limit the coded signal's spectral bandwidth, thereby allowing for high spectral efficiency (compared to other OCDMA systems) and compatibility with existing WDM systems with a rapidly reconfigurable set of codes. A four-user OCDMA system using polarization multiplexing is shown to operate at data rates of 2.5 Gb/s within a 40-GHz transparent optical window with a bit error rate (BER) better than 10/sup -9/ and a spectral efficiency of 25%.     

Filter-embedded design and its applications to passive components

A design in which a filter is embedded in a fiber fixed on a substrate is proposed. It was successfully applied to the fabrication of low loss fiber optic components for a single-mode fiber transmission system. These components have a wide operational temperature range. The design is easily adapted to a multifilter or multifiber component. Filter embedding is achieved in two ways. One is to insert a thin filter chip in a slit which is machined into a fiber fixed on a substrate by a dicing saw (filter inserted type). The other is to evaporate a filter film directly on a fiber end face and butt this fiber to another fiber on a guide groove on a substrate (filter evaporated type)     

The capacity region of a multiple-access discrete memoryless channel can increase with feedback (Corresp.)

The capacity of a single-input single-output discrete memoryless channel is not increased by the use of a noiseless feedback link. It is shown, by example, that this is not the case for a multiple-access discrete memoryless channel. That is, it is shown that the capacity region for such a channel is enlarged if a noiseless feedback link is utilized.     

A two wave theory of traveling-wave tubes and backward-wave oscillations

Starting from Pierce's small-signal TWT equations, a two-wave theory for complicated TWT's and BWO's is developed. Explicit gain expressions for TWT's with severs and velocity tapers are given. A detailed treatment is given of a BWA structure with a single-step velocity taper in the center. The BWO start oscillation current is calculated as a function of the taper strength. The effciency of a step velocity taper as a remedy for backward-wave oscillations in the higher passbands of a TWT is then analyzed. It is shown that a suitable taper can increase the start oscillation current by more than a factor of 10 without adverse effects on the TWT performance if the backward waye coupling impedance is low. A tube with a weak linear taper is analyzed by a perturbation technique and it is found that there is no significant difference between the start oscillation currents for tubes with weak linear or abrupt tapers of comparable strengths.     

Temperature control for food in pots on cooking hobs

A control system for the temperature of food in a cooking pot is introduced. The cooking pot is heated on a consumer cooking hob. The temperature of the pot side is used as input for the controller. It is measured by an infrared detector. The infrared detector is a thermopile. The sensor signal is evaluated by a rule-based control algorithm. The system is simple, reliable, and very user friendly. An exact temperature settlement in a consumer hob is available for the first time. The system is used for automatic cooking