Showing papers on "Insertion loss published in 1980"

Optical control of millimeter-wave propagation in dielectric waveguides

Abstract: We have demonstrated a new method for controlling millimeter-wave propagation in semiconductor waveguides-optical control. Phase shifts as high as 300°/cm at 94 GHz were observed accompanied by less than 1 dB insertion loss. A theoretical model has been developed to account in detail for the observed behavior. Extension of this technique to ultra-fast switching and gating of millimeter-wave signals is also described. Millimeter-wave pulsewidths as short as 1 ns and variable to tens of nanoseconds can readily be obtained.

Fundamental‐mode VHF/UHF minature acoustic resonators and filters on silicon

Abstract: Novel bulk acoustic‐wave high‐Q resonators and acoustically coupled resonator filters have been fabricated and operated at their fundamental half‐wavelength mode in the 200‐500‐MHz frequency range. These structures are fabricated on thin ZnO/silicon diaphragms with dimensions small enough to be incorporated within integrated circuits. Resonator Q’s near 2600 at the fundamental mode have been obtained and strong inter‐resonator acoustic coupling has been achieved yielding filters having insertion loss (untuned) as low as 5.5 dB.

General Extracted Pole Synthesis Technique with Applications to Low-Loss TE/sub011/ Mode Filters

Abstract: A novel synthesis technique is developed for two-port networks which possess finite real frequency transmission zeros. The low-pass prototype is synthesized in the form of a network with complex conjugate symmetry where the real frequency transmission zeros are extracted from both ends and realized by simple resonators separated by phase shifters. The remaining transmission zeros are realized by the central part of the filter in the form of a cross-coupled double array. This prototype is particularly suitable for designing waveguides bandpass filters and each real frequency transmission zero is independently tunable. Furthermore, in the case of the most complex transfer function with all possible types of transmission zeros, the realization requires only one type of coupling which is necessary in the important case of TE/sub011/ cylindrical mode cavity resonators. The general synthesis technique is given and the process illustrated by a nontrival example. Additionally, from the results of a computer program based upon the synthesis techniques, the important differences between the possible prototype forms for the same transfer function resulting from extracting the transmission zeros in different orders are cited.

Traveling wave optical modulator using a directional coupler LiNbO 3 waveguide

Abstract: Fabrication methods for low drive voltage and broad-band LiNbO 3 waveguide directional coupler optical modulator are described. Optical waveguides were prepared by conventionaly Ti in-diffusion into LiNbO 3 c -cut plate. To obtain wide-band frequency response, traveling wave electrodes were used. Electrode characteristic impedance measured by time domain reflectometry method coincided well with the calculated value by conformal mapping. Measured electrode conductor losses followed square root of frequency. To reduce electrode conductor losses, asymmetric and 3-μm thick Al electrodes were used. Directional coupler optical modulator frequency response was analyzed, using the phase difference average value along the propagation directions. Calculated value by this method coincided well with measured value obtained by a swept frequency technique. The characteristics of this modulator at the 1.317-μm wavelength are as follows: 100 percent modulation voltage is 4 V, extinction ratio is 17 dB, optical insertion loss is 5.4 dB, 3-dB bandwidth is 3.6 GHz, and rise time is about 400ps.

Microoptic grating multiplexers and optical isolators for fiber-optic communications

Abstract: As new optical devices for increasing further the utility of and to expand the application of fiber-optic communications, grating multiplexers and isolators have been developed for 0.8 μm band employing microoptic approach. The development of these devices is the subject of this paper. The devices have desirable features of small size, compactness, high optical performances, and high reliability. The grating multiplexer consists of a graded-index rod, a blazed reflection grating replicated onto the graded-index rod slanting facet or a wedge facet, and an input-output fiber array. Simple calculations have been done to determine necessary element parameters for a given channel spacing. Experimental results are presented for five-channel multiplexers devised using a SELFOC®lens. Around 3 dB insertion loss and less than -30 dB crosstalk have been obtained for about 35 nm channel spacing in overall device size of 18 \times 13 \times 50 mm. Faraday rotation optical isolators for 0.8 μm band have been miniaturized by employing an efficient paramagnetic glass Faraday rotator, a magnet with a through hole and a folded optics in the Faraday rotator. The path number in the folded optics has been optimized in terms of trading-off between the magnet size and the insertion loss. A 0.9 dB insertion loss including fiber coupling loss and 36 dB isolation have been obtained in overall device size of 24 \times 24.5 \times 42 mm. Results on the temperature and wavelength dependence of the isolation are also presented. In addition, fundamental properties of optical circulators for 0.8 μm band and optical isolators and circulators both for 1.3 μm band, developed as extended modifications of the optical isolators for 0.8 μm band, are briefly described.

Optical waveguide tap with infinitesimal insertion loss.

Abstract: The novel fluctuation characteristics predicted for two-photon coherent-state radiation make possible high signal-to-noise ratio detection from a directional coupler that is very weakly linked to an information-bearing optical waveguide.

Optical demultiplexer using a silicon echelette grating

Abstract: An echelette grating is fabricated on a silicon surface by anisotropic etching. A five channel demultiplexer using this grating for a wavelength-division-multiplexing system is developed in the 0.8-μm wavelength region. The wavelength spacings are 250 A. This system's insertion loss for five channels is 1.4, 1.1, 1.1, 1.1, and 1.2 dB, respectively, and crosstalk levels are <-30 dB.

LiNbO3 coupled-waveguided TE/TM mode splitter

Abstract: A novel optical TE/TM mode splitter was fabricated using Ti‐diffused LiNbO3 coupled waveguides. This splitter can spatially separate the TE and TM mode components and is compatible with single‐mode fiber systems. Crosstalk less than −20 dB was realized at 1.15‐μm wavelength. Optical insertion loss was 1.7 dB.

Total switching of unpolarized fiber light with a four-port electro-optic liquid-crystal device

Abstract: A liquid-crystal switch capable of switching nearly 100% of unpolarized light from one multimode fiber to another had been conceived and demonstrated experimentally. The switch uses a double interaction with a single layer of nematic liquid crystal in which the liquid alignment is initially in plane at 90° to the light propagation. This four-fiber optical reversing switch has a simple structure, a low insertion loss, and a low operating voltage. It should find a wide range of applications in fiber-optic communication systems.

A Metal-to-Dielectric Waveguide Transition with Application to Millimeter-Wave Integrated Circuits

Abstract: In this paper we describe the development of an efficient, low-loss transition from a conventional metal waveguide to a planar dielectric guide of rectangular cross section. Such a transition finds important application in millimeter-wave integrated circuits. We show that for a given length of the flared horn used for launching energy into the dielectric waveguide, the insertion loss of the transition can be reduced to a very low figure by choosing the flare angle of the horn appropriately.

Design of Loaded-Line p-i-n Diode Phase Shifter Circuits

Abstract: The design of three types of loaded-line p-i-n diode digital phase shifter circuits is presented. The three configurations considered are 1) main line mounted, 2) stub mounted, and 3) switchable stub length. Expressions for various design parameters are derived. Calculations show that for the 22.5/spl deg/ phase bit the maximum bandwidths for three circuits are 22.7, 19.2, and 18.4 percent, respectively. Starting from the p-i-n diode parameters, optimum designs of these circuits for obtaining minimum insertion loss, maximum bandwith, and minimum size are also discussed. It is found that the switchable stub length type configuration is suitable when nearly ideal p-i-n diodes are used while stub mounted type configuration is suitable for nonideal diodes. Experimental and theoretical performance (bandwidth and insertion loss) of stub mounted type circuits are compared and found to be in good agreement.

Polarization-independent optical circulator: an experiment

Abstract: Many kinds of optical devices are being researched in various countries for application in optical fiber communication. Some devices have polarization-dependent characteristics that cause a decrease in the coupling efficiency of the optical fibers. This paper proposes a configuration method using an optical circulator whose characteristics are independent of the polarization condition of the incoming light. Using components such as YIG crystals, polarization prisms, compensating plates, and magnet rings, it was experimentally confirmed that the insertion loss and the isolation were 3.7 dB and 10–20 dB, respectively, at λ = 1.27 μm and that the polarization dependence was greatly decreased.

Computer-controllable wedged-plate optical variable attenuator

Abstract: A computer-controllable variable optical attenuator has been developed and tested that has a wide dynamic range, wide spectral range, and is suitable for applications with high peak and average power laser sources. The device is based on Fresnel transmission through two pairs of wedged plates. A 35-dB dynamic range, an insertion loss of 1%, a precision of better than 1% and beam offset and deflection of <0.5 mm and 0.5 mrad, respectively, are demonstrated.

Variable attenuator for use in single-mode fiber transmission systems

Abstract: A novel compact optical variable-attenuator with a wide dynamic range for use in single-mode fiber transmission systems has been developed. Attenuation rate can be continuously adjusted by changing the distance between the end faces of the two fibers in the V-channel on a concave surface. The calculated insertion loss is <0.5 dB; the dynamic range of 30 dB is attained by <2.5 mm end separation. The calculated losses were verified experimentally. Reproducibility of the attenuation is within 0.5 dB.

Optical grating multiplexer in the 1.1-1.5 μm wavelength region

Abstract: Experimental results of a multiplexer using a diffraction grating for a wavelength-division-multiplexing transmission system are described. The multiplexer has 10 channels and a wavelength spacing of 36.2 nm in the 1.1-1.5 μm wavelength region. Minimum insertion loss for each channel was less than 2.2 dB.

Band stop filter and circuit arrangement for common antenna

Abstract: In a band stop filter having a plurality of series resonating circuits, and coaxial cables connected between the series resonating circuits, the length of each of the coaxial cables is made either shorter or longer than quarter wavelength at the center frequency. With this arrangement, asymmetry is introduced in the insertion loss vs frequency characteristic curve so that the curve is sharper than the symmetrical curve in a given range, resulting in a reduction of insertion loss at a transmission band which resides either above or below the center frequency. Two band stop filters may be combined to constitute an antenna coupler for connecting a transmitter and a receiver to a common antenna. Each of the series resonating circuits used in the band stop filter may be constructed of a quarter wavelength coaxial resonator, which functions as a parallel resonating circuit, and a loop-like coaxial cable, which functions as a coupling capacitor.

Coupler having arbitrary impedance transformation ratio and arbitrary coubling ratio

Abstract: An impedance transforming coupler is disclosed which may be used as a power divider or power combiner at microwave frequencies. The power division or power combination ratio is arbitrary, and the impedance transformation ratio is arbitrary. These couplers may be used in a circuit to power-combine amplifiers. The insertion loss of the circuit is low and the bandwidth is improved by an order of two to one over prior art systems which had separate circuits for matching the impedance and providing power combining. The coupler is optimally a branch line coupler having four curved branches a quarter wavelength long at the center frequency. The output ports are 90° out of phase. Simple formulas are given relating the desired admittances of each of the four branches to k, the desired power coupling ratio, and Y, the desired admittance transformation ratio.

Microwave switching with parallel-resonated GaAs FETS

Abstract: The use of GaAs FETs as microwave switches is discussed, and the feasibility of such devices for applications requiring ultra low dc power consumption, low insertion loss, and bidirectionality is demonstrated. A discrete SPST switch consisting of two parallel-resonated single-gate GaAs FETs exhibited 0.5 db insertion loss with 25 db isolation at 8.5 GHz. The first monolithic SPDT switch incorporating parallel-resonated GaAs FETs is also reported.

Method and apparatus for measuring the insertion loss of a splice in an optical fiber

Abstract: Apparatus for field measurement of the insertion loss of a splice between one ends of first and second optical fibers comprises an integrating sphere that is split along its axis and which has a fiber input port, a pair of spaced-apart padded holes on the axis for receiving associated fibers so as to center the splice inside the sphere, and an output port receiving one end of a fiber bundle which couples diffuse light in the sphere to a radiometer. A baffle plate in the sphere prevents light rays from the splice being incident on the output port. The splice loss is determined by inserting the one end of the first fiber into the input port, with the other end illuminated by light from a source, and reading a reference level of light coupled to the radiometer. The two fibers are then spliced together and the splice located inside the sphere. With light of the reference level now incident on the splice, light scattered thereby is diffused in the sphere and coupled by bundle fibers to the radiometer which indicates the radiant power of scattered light. The splice loss is a function of the ratio of the indications of scattered and reference light.

An X-band SOS resistive gate&#8212;insulator&#8212;semiconductor (RIS) switch

Abstract: The new X-Band Resistive Gate-Insulator-Semiconductor (RIS) switch has been fabricated on silicon-on-sapphire, and its equivalent circuit model characterized. An RIS SPST switch with 20-dB ON/OFF isolation, 1.2-dB insertion loss, and power-handling capacity in excess of 20-W peak has been achieved at X band. The device switching time is on the order of 600 ns, and it requires negligible control holding current in both ON and OFF states. The device is compatible with monolithic integrated-circuit technology and thus is suitable for integration into low-cost monolithic phase shifters or other microwave integrated circuits.

High Performance SAW Resonator Filters for SATELLITE Use

Abstract: We have developed a surface a coustic wave resonator n oise suppression filter for use in a low-noise earth-satellite frequency source. This narrowband 500 MHz filter was selected for satellite application because a complex phase-locked loop system is the only other way to achieve the required n oise performance. Also, the SAW device is small in size, has low insertion loss, relatively high power capacity, and is relatively insensitive to adverse environmental conditions. A new reflector weighting scheme, utilizing withdrawn and segmented lines, resulted in 22 d8 off-resonance rejection with less than one dB ripple for this two-port single-pole device on quartz. Unloaded Q values in excess of 22,000 (1.06 times the published material Q limit), and an insertion loss of 1.7 dB. have been achieved. The power handling capacity of this device which is to be operated at +13 dBm input power, is discussed in detail including damage mechanisms. Radiation exposure of 1 MRAD (gama ray) resulted in no change in device performance. Further, the sensitivity to acceleration was found to be 3 x 10-10/g and severe vibration tests prove the aevices will survive the pyrotechnic shock assoicated with rocket interstage separation.

Nonblocking 8×8 optical matrix switch for fibre-optic communication

Abstract: A compact nonblocking 8×8 optical switch composed of 64 pentagonal prisms is described. The switch dimensions are 60×120×120 mm. Insertion loss was from 1.7 to 4.0 dB, and switching repeatability was 1 dB.

A Novel Polarization-Independent Beam Splitter

Abstract: This paper presents the design and experimental results of a novel broad-band quasi-optical polarization-independent beam splitter. The novel beam splitter consists of parallel metallic strips formed on a dielectric sheet. The width and spacing of the metallic strips and thickness of the dielectric sheet are optimized. This experimentally manufactured 3-dB beam splitter has a frequency bandwidth from 80 to 110 GHz, and the transmission and reflection coefficients for mutually orthogonal polarisation are within 3/spl plusmn/0.5 dB over this entire frequency band. The insertion losses are 0.2 dB over the abovementioned frequency band. The obtained insertion losses are less than that obtained with any other quasi-optical polarisation-independent beam splitter presented in the literature to date. This type of beam splitter holds great promise as a device for constructing signal-multiplexing and demultiplexing circuits in the millimeter-wave region and above.

A Quadriphase Fin-Line Modulator

Abstract: A hybrid-coupled quadriphase rnodulator which has been realized in fin-line technique is described It operates over a 15-percent frequency band around 15 GHz with an insertion loss of 17 dB The circuit has been scaled to twice the operating frequency The insertion loss then amounts to 22 dB Furthermore, it is shown experimentally that the performance of the modulator does not degrade if the dimensions of the waveguide housing are altered to amounts of up to 10 percent

Microwave switching power divider

Abstract: A microwave switching power divider for selectively dividing and switching microwave energy among a plurality of outputs to other microwave devices includes a pair of parallel, spaced-apart circular ground planes defining a microwave cavity with multi-port microwave power distributing switching circuitry formed on opposite sides of a thin circular dielectric substrate disposed beween the ground planes. The power distributing circuitry includes a conductive disk located at the center of the substrate and connected to a source of microwave energy. A plurality of tapered radial power dividing transmission lines for intercepting the standing waves are symmetrically disposed about and connected to the conductive disk. Within each line, a high speed, low insertion loss switching diode and a DC blocking capacitor are connected in series between the outer end of a transmission line and an output port. A high impedance, microwave blocking DC bias choke is connected between each switching diode and a source of switching current. The switching source forward biases the diodes to couple microwave energy from the conductive disk to selected output ports and, to associated antenna elements connected to the output ports to form a synthesized antenna pattern. Output port impedance is held within a desired range by choice of cavity and power distribution circuitry dimensions.

Compact wavelength multiplexer using optical-fiber pieces

Abstract: The optical-wavelength-division multiplexer reported here is composed of three multimode fiber pieces with dielectric multilayers evaporated on the ends of the fibers, which have been polished obliquely or squarely. The working faces of these fibers are bonded together in a crossed V groove to duplex two wavelengths (λ = 0.82 and 1.2 μm). The far ends of the joined fiber pieces are left intact for splicing with fiber cables or are terminated with connector ferrules for connection. The multiplexer is small (1 cm square) and lightweight (1.5–3 g). It also shows low insertion loss (1 dB) and cross-talk level (below −40 dB). We have estimated that the cost of this type of component can be reduced to 1 order of magnitude lower than that of conventional lens and mirror types.

Dual gate GaAs m.e.s.f.e.t. phase shifter with gain at 12 GHz

Abstract: A dual gate m.e.s.f.e.t. phase shifter is described with 4 dB insertion gain at 12 GHz and more than 100° linear continuous phase shift as a function of the d.c. voltage applied to the controlling gate electrode.

A Quasi-optical Single Sideband Filter Employing A Semiconfocal Resonator

Abstract: We describe a single sideband filter designed to have low insertion loss when used with microwave radiometer systems incorporating a feedhorn of relatively large beam divergence angle The device we discuss is a type of Fabry-Perot interferometer empIoying one plane and one spherical mirror which form a near semiconfocal resonant cavity Measurements on a prototype device operating at v~1OO GHz with a f/D~4 feedhorn and a 14-GHz IF frequency are presented,