Showing papers on "Insertion loss published in 1990"
TL;DR: In this paper, passive inductors and LC filters fabricated in standard Si IC technology are demonstrated, and Q-factors from three to eight and inductors up to 10 nH in the gigahertz range have been realized.
Abstract: Passive inductors and LC filters fabricated in standard Si IC technology are demonstrated. Q-factors from three to eight and inductors up to 10 nH in the gigahertz range have been realized. Measurements on a five-pole maximally flat low-pass filter give midband insertion loss and -3 dB bandwidth close to the nominal design values of 2.25 dB and 880 MHz. >
433 citations
Patent•
03 Apr 1990TL;DR: In this article, a rotary joint for singlemode optical fibers is proposed, having a fixed and a rotating part to permit the transmission of optical signals across a rotational interface (such as a winch or turret) with minimal insertion loss and low reflections.
Abstract: The invention is a rotary joint for singlemode optical fibers, having a fixed and a rotating part to permit the transmission of optical signals across a rotational interface (such as a winch or turret) with minimal insertion loss and, in particular, low reflections (good return loss). There is no need of conversion to electrical signals; the device is passive. It may be use an oil of refractive index matched to that of the glass fibers and to that of fiber tapers or lenses used to expand the beam emitted from one fiber and contract it for transmission into the other fiber. The device is bidirectional. By use foil, through precision techniques for building and mounting the optical and mechanical components, and by use of advanced bearings, both the insertion loss and unwanted reflections (return loss) can be minimized, thereby making it suitable for use with singlemode fiber. Insertion loss can be further reduced in conjunction with index-matching fluid by using optical elements (lenses, tapers, fibers) having angled or curved facets rather than perpendicular facets. Oil filling has the further advantage of pressure compensation allowing the device to operate at any ambient pressure. Lenses having curved surfaces can be accommodated by the use of fluid having a refractive index different from that of the lens material.
228 citations
TL;DR: In this article, the design and performance of multichannel amplitude-modulated (AM) vestigial-sideband (VSB) lightwave cable television (CATV) systems are described.
Abstract: The design and performance of multichannel amplitude-modulated (AM) vestigial-sideband (VSB) lightwave cable television (CATV) systems are described. Requirements on linearity and noise are derived, and factors limiting the performance of the laser transmitters and receivers are discussed. For the high-performance lasers the carrier-to-noise ratio and composite second- and third-order distortions are acceptable for video trunk systems. Impairments because of fiber reflections and dispersion and mode partition fluctuations in the laser are discussed. Feedforward, feedback, and predistortion are discussed; difficulties with each prevent immediate application. The use of LiNbO/sub 3/ external modulators and high-power solid-state lasers is considered. The third-order distortion and insertion loss of the modulator more than counteract the high available laser power (100 mW), making this alternative unattractive unless a third-order linearizer can be implemented. >
176 citations
04 Dec 1990
TL;DR: In this paper, a two-pole monolithic ladder filter operating in the 1-1.5 GHz range has been demonstrated, which has a bandwidth of 30 MHz at 1 GHz and an insertion loss of about 1 dB.
Abstract: It is demonstrated that completely monolithic two-pole filters can be fabricated on silicon substrates using FBARs (film bulk acoustic resonators) and that these filters have low loss and reasonable bandwidth. A two-pole monolithic ladder filter operating in the 1-1.5 GHz range has been demonstrated. These filters (0.3*0.3*0.02 in) have a bandwidth of 30 MHz at 1 GHz and an insertion loss of about 1 dB. The small size serves to provide good shock and acceleration tolerance. Preliminary results on a stacked FBAR filter operated in high overtone mode show response up to 5.5 GHz. The authors review the development of FBAR technology, including piezoelectric film and membrane materials, fabrication techniques, temperature compensation schemes, and the progress made in processing monolithic filters. Issues relating to integration of FBARs with active circuits and IC processing compatibility are addressed. >
133 citations
Patent•
09 Jul 1990
TL;DR: In this paper, a stream of fluid medium is flowed through a fluid container which is electrically configured as a transmission line segment and which is connected to load a UHF or microwave oscillator, at a starting frequency which is chosen to provide a particularly strong shift in permittivity of the fluid medium.
Abstract: A system and method for monitoring conditions in a fluid medium. A stream of the fluid medium is flowed through a fluid container which is electrically configured as a transmission line segment and which is electrically connected to load a UHF or microwave oscillator. The oscillator is not isolated from the load, and is operated free-running, at a starting frequency which is chosen to provide a particularly strong shift in permittivity of the fluid medium, as the chemical reaction progresses. Preferably the frequency and insertion loss of the oscillator are monitored, to gauge the progress of the reaction.
128 citations
TL;DR: In this paper, a four-channel multiplexers and four-wavelength bandpass filters based on elliptical Bragg reflectors (EBRs) are discussed, where the EBRs are narrowband elliptical mirrors that can refocus light from an input waveguide to any one of a number of output waveguides.
Abstract: Four-channel multiplexers and four-wavelength bandpass filters based on elliptical Bragg reflectors (EBRs) are discussed. The channel spacing is 50 AA near 1.56 mu m. The EBRs are narrowband elliptical mirrors that can refocus light from an input waveguide to any one of a number of output waveguides. Spectrally, they perform similarly to Bragg reflectors. The devices were fabricated on silicon using silica-based waveguide technology. The elliptical gratings with 0.53- mu m periods were patterned using deep UV spatial frequency doubling photolithography. Multiplexers with single filtering and double filtering were demonstrated. With single filtering, the fiber-to-fiber insertion loss was 3.0+or-0.5 dB, and the crosstalk was -20 dB; with double filtering, the insertion loss was 4.0+or-0.5 dB, and the crosstalk was -30 dB. About 2 dB of this loss was due to coupling between the fibers and the waveguide. The additive loss associated with the EBR, including propagation, Bragg reflection, and coupling between input and output waveguides, was about 1 dB. >
105 citations
TL;DR: In this article, an adiabatic polarization splitter, fabricated with silica and silicon nitride films on a silicon substrate, was demonstrated, and a rejection of the unwanted polarization of −20 to −34 dB was achieved with single filtering and −35 to −45 dB with double filtering.
Abstract: An adiabatic polarization splitter, fabricated with silica and silicon nitride films on a silicon substrate, is demonstrated. A rejection of the unwanted polarization (cross talk) of −20 to −34 dB was achieved with single filtering and −35 to −45 dB with double filtering. The device had a 1.5 dB insertion loss and a very small wavelength dependence.
74 citations
TL;DR: In this paper, it was shown that the maximum modulation ratio in Fabry-Perot reflective electroabsorption modulators for a given insertion loss is solely a function of the ratio of the maximum to minimum absorption.
Abstract: We show theoretically that the maximum modulation ratio in Fabry–Perot reflective electroabsorption modulators for a given insertion loss is solely a function of the ratio of the maximum to minimum absorption. We increase this ratio by using thinner quantum wells than are conventionally used and obtain significantly improved performance. We obtain an insertion loss of 1.2 dB and a modulation ratio of 7.5 with a 5 V operating bias.
71 citations
TL;DR: In this article, the insertion loss of a spot-size transformer based on dual tapered waveguides is reduced by controlling the shape of the tapered portion of the transformer.
Abstract: The reduction of the insertion loss of a spot-size transformer based on dual tapered waveguides (DTW-SST) by controlling the shape of the tapered portion is discussed. The transformer is easily fabricated using a shadow mask sputtering method. A method is described for controlling independently the parameters of the tapered portion, such as the maximum taper angle, and length, and the position of tapered portion with respect to the edge of the shadow mask. A large transformation ratio (5 and 1/5) and a low insertion loss (0.7 dB) have been obtained. >
60 citations
26 Apr 1990
TL;DR: In this paper, a low-loss reflection-type analog phase shifter circuit is described, and experimental results are presented, which incorporates several design features to produce nearly 360 degrees of phase shift at X-band while achieving an insertion loss of only 4.8 dB with + or 0.5 dB of variation over all phase states.
Abstract: A low-loss reflection-type analog phase shifter circuit is described, and experimental results are presented. The circuit incorporates several design features to produce nearly 360 degrees of phase shift at X-band while achieving an insertion loss of only 4.8 dB with +or-0.5 dB of variation over all phase states. These results improve upon previously reported X-band performance by demonstrating a large phase shift range together with low attenuation and low amplitude variation with phase state. >
47 citations
TL;DR: In this paper, an optical analog link operating at 20 GHz with a 3-dB bandwidth of 5.2 GHz was demonstrated, and the link consisted of a CW laser, an integrated-optical intensity modulator, and a p-i-n diode detector connected by fibers; it was treated as a two-port RF device.
Abstract: An optical analog link operating at 20 GHz with a 3-dB bandwidth of 5.2 GHz was demonstrated. This link has an intermodulation-free dynamic range of 108 dB-Hz/sup 2/3/ and a maximum signal-to-noise ratio (SNR) of 155 dB-Hz. Previously reported direct modulation analog links have not been able to operate at 20 GHz and, even in the 10-GHz frequency range, have had 20-30-dB-poorer SNRs; externally modulated links are capable of high-frequency operation but have demonstrated 30-50-dB-poorer SNRs than the present link. The link consists of a CW laser, an integrated-optical intensity modulator, and a p-i-n diode detector connected by fibers; it contains no amplifiers. The link performance is evaluated at the RF ports, i.e. it is treated as a two-port RF device. It is noted that by simply using a detector with no rolloff and by reducing the modulator excess optical insertion loss to 3 dB, the RF insertion loss can be improved to -25 dB and the noise figure to 33 dB. >
TL;DR: In this article, the authors model the room temperature electroabsorption of coupled double quantum wells using a transfer matrix technique to calculate carrier wavefunctions and their overlaps and compare their behaviour with uncoupled multiple quantum wells with optical modulation in mind.
Abstract: The authors model the room temperature electroabsorption of coupled double quantum wells using a transfer matrix technique to calculate carrier wavefunctions and their overlaps. Their behaviour with an electric field is compared with uncoupled multiple quantum wells with optical modulation in mind. Consideration of wavefunctions and energy levels allows them to choose a coupled well structure with good optical modulation at a low electric field. By fitting three parameters once, they predict absorption spectra. These are used to assess coupled quantum wells within an asymmetric Fabry-Perot reflection modulator. Very low voltage operating characteristics were calculated allowing for a total fluctuation in the coupling barrier width of one monolayer: a contrast ratio of 2.1:1, an insertion loss of 3.3 dB and an applied voltage of only 0.7 V; alternatively, a very high contrast with an insertion loss of 9.4 dB operating at 2.2 V. However, these predictions may be difficult to fulfil in devices grown at present because of the built-in field within the intrinsic region of a p-i-n diode.
01 Apr 1990
TL;DR: In this article, Meixner's edge condition for the rectangular strip with loss is investigated and based on this condition and the analysis, a simple and accurate curve fitted approximation of the AC resistance is presented.
Abstract: The AC resistance is an important factor in determining the insertion loss of miniature MMIC circuits over their passband. The metallisation of an MMIC is in the form of rectangular strips. The paper gives detailed formulation and analysis of the isolated rectangular strip conductor. Meixner's edge condition for the rectangular strip with loss is investigated. It is found that such a condition is obeyed. Based on this condition and the analysis, a simple and accurate curve fitted approximation of the AC resistance is presented.
TL;DR: In this paper, the electro-absorptive properties of ≈ 150 A quantum wells in an asymmetric Fabry-Perot modulator (AFPM) with very low drive voltage was demonstrated.
Abstract: Using the electro-absorptive properties of ≈ 150 A quantum wells in an asymmetric Fabry–Perot modulator (AFPM), a normally-off reflection modulator with very low drive voltage was demonstrated. With this device contrasts of more than 6 dB at normal incidence in reflection have been achieved, with a voltage swing of only 3.5 V and ≤3 dB insertion loss.
TL;DR: Wavelength-selective characteristics in the AO module are established and the crosstalk from other wavelengths is found to be reduced by decreasing slightly the switching transfer efficiency.
Abstract: Optical integrated switching systems using collinear acoustooptic (AO) interactions for wavelength division multiplexing (WDM) systems are discussed. The AO switch module has excellent advantages compared to electrooptic switches. Optical WDM signals can be wavelength-selectively switched by frequency multiplexed surface acoustic waves. WDM switching systems are proposed as an application of this AO switch, and optical insertion loss, crosstalk, and optical frequency shift are discussed. Wavelength-selective characteristics in the AO module are established. The crosstalk from other wavelengths is found to be reduced by decreasing slightly the switching transfer efficiency. The wavelength-selective switching was experimentally demonstrated with a slab-type module of a 4-mm interaction region, where the WDM interval of 25.2 AA was realized. This wavelength interval can be decreased by increasing the interaction length. >
TL;DR: In this article, a low-loss microstrip matching circuit with large bandwidth for connecting a laser diode that has a nominal impedance of 2 Omega to a 50 Omega system is described, which utilizes a microstrip Chebyshev transformer without very wide line widths to obtain the match at a center frequency of 10.5 GHz with a bandwidth of 9 GHz.
Abstract: A low-loss microstrip matching circuit with large bandwidth for connecting a laser diode that has a nominal impedance of 2 Omega to a 50 Omega system is described. The technique utilizes a microstrip Chebyshev transformer without very wide line widths to obtain the match at a center frequency of 10.5 GHz with a bandwidth of 9 GHz, an insertion loss of less than 1.5 dB, and a reflection coefficient of better than -10 dB. >
TL;DR: In this article, the authors analyzed the transmission and reflection characteristics and wavelength chirping of a guided mode in a semiconductor intersectional optical switch-modulator by considering the electric field-induced refractive index variation along with the absorption loss variation.
Abstract: Transmission and reflection characteristics and wavelength chirping of a guided mode in a semiconductor intersectional optical switch-modulator are analyzed by considering the electric field-induced refractive index variation along with the absorption loss variation. The refractive index and absorption ratio, alpha /sub p/, is shown to determine the performance of the switch-modulator. A transmission port is suitable for a modulation with a high extinction ratio, low insertion loss, and small wavelength chirping. The insertion loss at the reflection port depends heavily on alpha /sub p/. A low insertion loss and high extinction ratio intersectional optical switch is possible when - alpha /sub p/ is higher than 10, which can be realized with a quantum box structure. >
07 May 1990
TL;DR: In this article, a broadband, 6-b monolithic microwave IC (MMIC) phase shifter and digital driver were combined on a single chip to realize a single-chip digital and microwave technologies.
Abstract: Digital and microwave technologies have been successfully combined on a single chip to realize a broadband, 6-b monolithic microwave IC (MMIC) phase shifter. It exhibits low insertion loss, good voltage standing wave ratio (VSWR), and exceptional phase performance with less than 3 degrees RMS phase error for all 64 phase states over the entire 7.2-10.2 GHz band. Compared to previous designs, the number of required control lines has been reduced by a factor of two due to the integration of the digital drive circuitry. Phase shifter and digital driver design, fabrication, and performance are described. >
08 May 1990
TL;DR: In this article, a PIN diode attenuator/limiter was used to achieve variable attenuation at X-band, while maintaining under 1.5 to 1 input and output voltage standing wave ratios (VSWRs).
Abstract: Monolithic GaAs PIN diode attenuator/limiter circuits have demonstrated 26 dB of variable attenuation at X-band, while maintaining under 1.5 to 1 input and output voltage standing wave ratios (VSWRs). Insertion loss is 0.8 dB at 10 GHz in the zero bias condition. Passive limiting provides 15 dB of isolation at RF input power of 2.0 W CW (continuous wave). These results are obtained using a vertical pin diode process on metallorganic chemical vapor deposition (MOCVD) material. >
TL;DR: In this article, the first low voltage, substrate access, reflective InGaAs/InP multi-quantum well modulator exploiting the enhanced performance obtainable through the use of an asymmetric Fabry-Perot cavity around the quantum well absorbing region is reported.
Abstract: The first low voltage, substrate access, reflective InGaAs/InP multi-quantum well modulator exploiting the enhanced performance obtainable through the use of an asymmetric Fabry-Perot cavity around the quantum well absorbing region is reported. This device utilises a low reflectivity AlInGaAs/InP multi-layer mirror (R~35%) on the substrate side of the quantum well region, and a high reflectivity metal mirror (R~95%) on the epitaxial side of the cavity. Devices have been fabricated which exhibit a reflectivity change of >30% and contrast ratio of 3 dB at 5 V bias, with a 1.8 dB insertion loss.
TL;DR: In this paper, a singlemode inline variable optical attenuator utilizing optical fiber tapers is discussed, which achieves axial separation between two tapers with beveled end faces aligned within a ceramic sleeve.
Abstract: A single-mode inline variable optical attenuator utilizing optical fiber tapers is discussed. Optical attenuation control is achieved through axial separation between two tapers with beveled endfaces aligned within a ceramic sleeve. Increased axial separation causes increased coupling loss between the two taper fundamental modes. Insertion loss of 75 dB with continuous 0.05 dB resolution, and reflection return loss of better than 58 dB have been realized. Theoretical studies indicate low polarization and wavelength dependence, and inherent insertion loss of >
TL;DR: In this article, a low-loss monolithic integration of a 3-dB waveguide coupler with twin photodetectors using largemode size guides, mirror coupling, and low-capacitance lateral detectors is demonstrated.
Abstract: Low-loss monolithic integration of a 3-dB waveguide coupler with twin photodetectors using large-mode size guides, mirror coupling, and low-capacitance lateral detectors is demonstrated. Waveguide-mirror integration introduces only approximately=1 dB optical insertion loss at 1.54 mu m wavelength, compared to top-illuminated detectors. Full balanced operation of the monolithic circuit with 33-dB local oscillator intensity noise suppression is demonstrated. >
NEC1
TL;DR: In this article, a polarization-independent LiNbO/sub 3/ strictly blocking 8*8 matrix switch has been developed with a relatively low insertion loss, below 12 dB, obtained by a reduction in bending loss, using a wide bent waveguide width.
Abstract: A polarization-independent LiNbO/sub 3/ strictly blocking 8*8 matrix switch has been developed. A relatively low insertion loss, below 12 dB, has been obtained by a reduction in bending loss, using a wide bent waveguide width. The switch has less than -18.7-dB crosstalk and about 85-V switching voltage at any incident polarization with 1.3- mu wavelength light. >
TL;DR: Optical interconnects for very large scale integration systems based on planar waveguide holograms are analyzed to enable the construction of various compact planar architectures with high interconnect density and low insertion loss.
Abstract: Optical interconnects for very large scale integration systems based on planar waveguide holograms are analyzed. The combination of low loss waveguides and multiplexed waveguide holograms allows the construction of various compact planar architectures with high interconnect density and low insertion loss. The long interaction lengths possible in planar structures result in high angular and wavelength selectivity. Holographic grating couplers and multiplexed planar holograms for 1-to-3 interconnects and 1-to-3 multiple wavelength interconnects were fabricated.
TL;DR: In this paper, the results of flashlamp pumping of the LiCAAIF6:Cr3+ (Cr:LiCAF) laser crystal are reported, and they have so far obtained slope efficiencies as high as 1.55% in a close-coupled, diffusely reflecting cavity.
Abstract: The results of flashlamp pumping of the LiCaAIF6:Cr3+ (Cr:LiCAF) laser crystal are reported. We have so far obtained slope efficiencies as high as 1.55% in a close-coupled, diffusely reflecting cavity. Based on the measured insertion loss of the presently available material, we predict that an efficiency of about 4% will be obtained when low-loss material becomes available. This extrapolated efficiency is comparable with the performance of a high-quality alexandrite laser rod in the same apparatus.
Patent•
21 Jun 1990
TL;DR: In this article, a dual mode surface acoustic wave filter with less undesired spurious vibration and a small insertion loss was obtained by forming the filter with a LiTaO 3 piezoelectric substrate of 36° Y rotation cut X direction propagation.
Abstract: PURPOSE: To obtain a longitudinal dual mode surface acoustic wave filter with less undesired spurious vibration and a small insertion loss even when the filter is used for a high frequency band of around 900MHz or the like by forming the filter with a LiTaO 3 piezoelectric substrate of 36° Y rotation cut X direction propagation. CONSTITUTION: Plural energy confinement resonators formed by three sets of IDTs 20-40, 21-41 arranged closely on a LiTaO 3 piezoelectric substrate 1 of 36° Y rotation cut X direction propagation and a couple of reflectors 50, 60, 51, 61 arranged at both sides of the 3 sets of IDTs are arranged in parallel so that each surface acoustic wave propagation direction is in parallel. Furthermore, the plural energy confinement resonators are connected in cascade as multi-stage and the relation of NT≤50 and 15≤(W/P)≤90 is satisfied, where NT is a total pair number of electrode fingers of the IDT of each energy confinement resonator, W is the crossing width and P is a pitch of the electrode finger. COPYRIGHT: (C)1993,JPO&Japio
TL;DR: It is shown that the basic 2 x 2 switch can be extended to form a N x N rearrangeable permutation network.
Abstract: The design and experimental results of a new 2 × 2 optical routing switch based on liquid crystal is reported. The switch uses nematic liquid crystal for polarization beamsplitting and ferroelectric liquid crystal for polarization rotation. The polarization insensitive, broadcast capable, full duplex switch has a signal-to-crosstalk ratio of ~20 dB, a switching speed below 250 μs and a measured insertion loss of 1.4 dB. We show that the basic 2 × 2 switch can be extended to form a N × N rearrangeable permutation network.
04 Dec 1990
TL;DR: Oscillator sustaining stage circuitry incorporates low-1/f noise modular RF amplifiers, Schottky-diode ALC, and a miniature 2-pole helical filter for suppression of HBAR adjacent resonant responses to confirm that state-of-the-art levels of short-term frequency stability have been obtained.
Abstract: High-overtone, bulk acoustic resonators (HBAR) that exhibit 9-dB insertion loss and loaded Q values of 80000 at 640 MHz with out-of-phase resonances occurring every 2.5 MHz have been designed. These resonators have been used as ovenized frequency control elements in very low phase noise oscillators. The oscillator sustaining stage circuitry incorporates low 1/f noise, modular RF amplifiers, Schottky-diode ALC, and a miniature two-pole helical filter for suppression of HBAR adjacent resonant responses. Measurement of oscillator output signal flicker-of-frequency noise confirms that levels of short-term frequency stability characterized by Sy(100 Hz)=5*10/sup 26/ have been obtained. The sustaining stage circuit contribution to resulting oscillator flicker-of-frequency noise is 7 to 10 dB below that due to the resonators themselves. >
08 May 1990
TL;DR: In this paper, an MSW bandpass filter with combined magnetic units composed of main and submagnetic units was developed, whose volume was reduced to one fifth that of conventional yttrium-iron-garnet (YIG)-sphere filters.
Abstract: An MSW (magnetostatic wave) bandpass filter with combined magnetic units composed of main and submagnetic units has been developed. Its volume is reduced to one fifth that of conventional yttrium-iron-garnet (YIG)-sphere filters. The filter can be tuned mechanically and keep the same shape of transmission response at 2.5 approximately 2.75 GHz. The insertion loss can be kept less than 3 dB within 20-MHz bandwidth by adjusting the magnetic field distribution. >
04 Dec 1990
TL;DR: In this article, two SAW filters were designed and realized at 1.7 GHz and 2.5 GHz, which correspond to electrode widths of 0.6 mu m and 0.4 mu m, respectively.
Abstract: The authors present SAW (surface acoustic wave) filter techniques suitable for low-loss operation. These techniques are based on a newly developed submicron photolithography as the appropriate mass-production low-cost pattern fabrication process. Two filters have been designed and realized at 1.7 GHz and 2.5 GHz, which corresponds to electrode widths of 0.6 mu m and 0.4 mu m, respectively. The filters provide an insertion loss of 6 dB and a stopband rejection of about 40 dB. The dual-track technique has been applied with the advantage of local separated structure parts responsible for low-loss operation and high selectivity. >