共查询到20条相似文献,搜索用时 500 毫秒
1.
The magnitudes of linear electrooptic coefficients r 13 and r 33 in Zn:LiTaO3 repoled channel waveguides are reported. The measurements were made at 0.633-μm wavelength using a Fabry-Perot interferometer. The waveguides were produced by diffusion from the vapor phase at a temperature above the Curie temperature. For full recovery of the Pockels effect, an electric field of 200 V/cm is needed during repoling. The measured values of r 13 and r 33 at 32-MHz modulation frequency are 7.2 and 30.3 pm/V, respectively. The difference between unclamped and clamped coefficients is comparable to that from bulk crystals. Measurements were also made on Ti:LiNbO3 waveguides that did not require repoling, and good agreement with bulk crystal values was obtained 相似文献
2.
Both absolute and relative nonlinear optical coefficients of six nonlinear materials measured by second-harmonic generation are discussed. A single-mode, injection-seeded, Q -switched Nd:YAG laser with spatially filtered output was used to generate the 1.064-μm fundamental radiation. The following results were obtained: d 36(KD*P)=0.38 pm/V, d 36(KD*P)=0.37 pm/V, |d 22(BaB 2O4)|=2.2 pm/V, d 31(LiIO3 )=-4.1 pm/V, d 31(5%MgO:MgO LiNbO3)=-4.7 pm/V, and d eff(KTP)=3.2 pm/V. The accuracy of these measurements is estimated to be better than 10% 相似文献
3.
Self-aligned high-frequency InP/InGaAs double heterojunction bipolar transistors (DHBTs) have been fabricated on a Si substrate. A current gain of 40 was obtained for a DHBT with an emitter dimension of 1.6 μm×19 μm. The S parameters were measured for various bias points. In the case of I C=15 mA, f T was 59 GHz at V CE=1.8 V, and f max was 69 GHz at V CE=2.3 V. Due to the InP collector, breakdown voltage was so high that a V CE of 3.8 V was applied for I C=7.5 mA in the S -parameter measurements to give an f T of 39 GHz and an f max of 52 GHz 相似文献
4.
An LiNbO3 optical integrated circuit pigtailed with two single-mode fibres, which allows time-division two-dimensional velocity measurement, is discussed. To detect time-division multiplexed beat signals corresponding to velocity components v X and v γ of a moving object, a waveguide switch is integrated on a Z -propagating LiNbO3 substrate of 28×7 mm2 in addition to a waveguide interferometer with a frequency shifter. In the optical IC, either v X or v γ could be measured selectively with signal-to-noise ratio of 20 dB by driving an electronic gate placed after a photodiode in synchronization with the waveguide switch 相似文献
5.
Demonstrates a narrowband (≈1 nm) LiNbO3 acoustically tunable optical filter with a tuning range adequate to span the 1.3-1.55 μm wavelength range, exploiting the considerable advantages of an unconventional x -cut design 相似文献
6.
An integrated optical frequency shifter that utilizes guided-wave acoustooptic Bragg diffractions in cascade from two tilted- and counterpropagating-surface acoustic waves is reported. The doubly and frequency-shifted diffracted light propagates in a fixed direction, but spatially resolved from the incident light, irrespective of the magnitude of frequency tuning. A device fabricated in a Y -cut LiNbO3 planar waveguide has demonstrated desirable characteristics, including single-sideband suppressed-carrier properties, a frequency shift centered at 1 GHz, a tunable bandwidth of 165 MHz, a linear dynamic range greater than 41 dB, and high efficiency at the optical wavelength of 0.63 μm. These preliminary results suggest that a compact integrated acoustooptic frequency shifter module capable of multigigahertz center frequency and gigahertz bandwidth can be realized in a common LiNBO3 substrate 0.2 cm×1.0 cm×1.5 cm in size 相似文献
7.
An In0.41Al0.59As/n+-In0.65 Ga0.35As HFET on InP was designed and fabricated, using the following methodology to enhance device breakdown: a quantum-well channel to introduce electron quantization and increase the effective channel bandgap, a strained In0.41Al0.59As insulator, and the elimination of parasitic mesa-sidewall gate leakage. The In0.65Ga0.35As channel is optimally doped to N D=6×1018 cm-3. The resulting device (L g=1.9 μm, W g =200 μm) has f t=14.9 GHz, f max in the range of 85 to 101 GHz, MSG=17.6 dB at 12 GHz V B=12.8 V, and I D(max)=302 mA/mm. This structure offers the promise of high-voltage applications at high frequencies on InP 相似文献
8.
Reports a theory for calculating the coupling length L c of Ti:LiNbO3 single-mode waveguide directional couplers from process parameters and operating wavelength. Estimates are accurate to within a factor of 2 compared with published experimental results for z -cut y -propagating LiNbO3 devices for 0.63 μm⩽λ⩽1.56 μm. Use of this formalism to assess acceptable process parameter and wavelength tolerances is demonstrated 相似文献
9.
Shaping the digital switch 总被引:1,自引:0,他引:1
A procedure is given for shaping 1×2 digital switches on x - or y -cut LiNbO3/LiTaO3 for prescribed values of crosstalk in order to reduce the voltage-length product. The method is based on a normal mode analysis using ordinary coupled mode theory parameters and a known solution for shaped branches. A factor of three improvement in voltage-length product is obtained, compared to linear branches 相似文献
10.
Scherrer D. Kruse J. Laskar J. Feng M. Wada M. Takano C. Kasahara J. 《Electron Device Letters, IEEE》1993,14(9):428-430
The low-power microwave performance of an enhancement-mode ion-implanted GaAs JFET is reported. A 0.5-μm×100-μm E-JFET with a threshold voltage of V th=0.3 V achieved a maximum DC transconductance of g m=489 mS/mm at V ds=1.5 V and I ds=18 mA. Operating at 0.5 mW of power with V ds=0.5 V and I ds =1 mA, the best device on a 3-in wafer achieved a noise figure of 0.8 dB with an associated gain of 9.6 dB measured at 4 GHz. Across a 3-in wafer the average noise figure was F min=1.2 dB and the average associated gain was G a=9.8 dB for 15 devices measured. These results demonstrate that the E-JFET is an excellent choice for low-power personal communication applications 相似文献
11.
A single-stage low-sidelobe weighted-coupled integrated acoustooptic tunable filter (IAOTF) operating at the optical wavelength of 1.31 μm has been realized on a Y -cut X -propagating LiNbO3 substrate for the first time. The weighted-coupling, which enabled the achievement of low-sidelobe levels, was facilitated by focused surface acoustic waves generated by a curved interdigital transducer. First sidelobe levels as low as -17.6 dB have been obtained. Optical bandwidth of 4 nm and tuning range of 170 nm for an interaction length of 6 mm were also accomplished 相似文献
12.
《Electron Devices, IEEE Transactions on》1990,37(1):153-158
The fabrication of a silicon heterojunction microwave bipolar transistor with an n+ a-Si:H emitter is discussed, and experimental results are given. The device provides a base sheet resistance of 2 kΩ/□ a base width 0.1 μm, a maximum current gain of 21 (V CE=6 V, I c=15 mA), and an emitter Gummel number G E of about 1.4×1014 Scm-4. From the measured S parameters, a cutoff frequency f t of 5.5 GHz and maximum oscillating frequency f max of 7.5 GHz at V CE=10 V, I c=10 mA are obtained 相似文献
13.
McDermott M.G. Sweeney C.N. Benedek M. Borelli J.J. Dawe G. Raffaelli L. 《Microwave Theory and Techniques》1990,38(9):1183-1190
Two technologies are demonstrated whereby high-Q , vertical-structure, abrupt-junction varactor diodes are monolithically integrated with 0.25-μm GaAs MESFETs on semi-insulating GaAs substrates for multifunction millimeter-wave monolithic circuit applications. Diodes with various anode sizes have been realized with measured capacitance swings of >2.1:1 from 0 V to -4 V and series resistances of approximately 1 Ω. Diodes having a zero bias capacitance of 0.35 pF have Q 's of >19000 (50 MHz) with -4 V applied to the anode. Under power bias conditions, the MESFETs have a measured gain of >6 dB at 35 GHz with extrapolated values for f t and f max of 32 GHz and 78 GHz, respectively. Using these technologies, a monolithic Ka -band voltage controlled oscillator (VCO) containing a varactor diode, a 0.25-μm GaAs MESFET, and the usual MMIC passive components has been built and tested. At around 31 GHz, the circuit has demonstrated 60-mW power output with 300 MHz of tuning bandwidth 相似文献
14.
Schubert E.F. Tsang W.T. Fueur M.D. Mankiewich P.M. 《Electron Device Letters, IEEE》1988,9(3):145-147
SiO2 insulator is on top of an InP layer; current transport occurs, however, an in adjacent n-type Ga0.47In0.53As:Sn layer. A transconductance of g m=300 mS/mm is obtained from depletion-mode MISFETs with a gate length of 1.2 μm. This MIS (metal-insulator-semiconductor) junction has a symmetric current-voltage characteristic and a low-leakage current of ~1 nA at ±2 V. High-frequency S -parameter measurements performed b probing devices on the wafers yield a unity current gain frequency of F t=22.2 GHz and a maximum frequency of oscillation f max=27 GHz 相似文献
15.
A theoretical investigation of Si/Si1-xGex heterojunction bipolar transistors (HBTs) undertaken in an attempt to determine their speed potential is discussed. The analysis is based on a compact transistor model, and devices with self-aligned geometry, including both extrinsic and intrinsic parameters, are considered. For an emitter area of 1×5 μm2, an f t of over 75 GHz and f max of over 35 GHz were computed at a collector current density of 1×10 5 A/cm2 and V CB of 5 V 相似文献
16.
Canarelli P. Benko Z. Hielscher A.K. Curl R.F. Tittel F.K. 《Quantum Electronics, IEEE Journal of》1992,28(1):52-55
The nonlinear optical characteristics of AgGaS2 were investigated by measuring visible parametric fluorescence with a pump wavelength of 600 nm. A value of d 36 [AgGaS2 ]=31±5×10-12 m/V for the nonlinear coefficient was determined. The temperature dependence of phase matching up to 100°C was studied. A significant temperature effect, although much smaller than for LiNbO3, was found and results in a change in the infrared difference frequency generated of ~0.6 cm-1 -°C-1 相似文献
17.
The second-order nonlinear coefficients measured in proton-exchanged LiNbO3 as a function of annealing time are discussed. Measurements of reflected second-harmonic power indicate that the second-order nonlinear coefficient d 33 is reduced to 60% of the bulk value as a result of proton exchange in pure benzoic acid. It is also shown that annealing restores the d -coefficients to almost the original value of the virgin crystal. For example, recovery to ~90% of the bulk value was obtained for a sample with a 0.3-μm-bulk proton-exchanged layer, annealed for 10 h at 350°C 相似文献
18.
Jungerman R.L. Johnsen C. McQuate D.J. Salomaa K. Zurakowski M.P. Bray R.C. Conrad G. Cropper D. Hernday P. 《Lightwave Technology, Journal of》1990,8(9):1363-1370
The design and characterization of the first integrated optic modulator for a commercial instrument application are described. Alternative forms of modulation, including direct laser current modulation and optical heterodyne techniques, are reviewed for the application, which requires modulation to 20 GHz. The advantages of an integrated optic modulator fabricated using titanium in-diffused lithium niobate are discussed. Performance tradeoffs between x -cut and z -cut LiNbO3 including bandwidth, modulation efficiency, bias point stability, and acoustic resonances are detailed. The x -cut device is found to give the best overall performance for this instrument application. Device reliability and testing, including temperature cycling, humidity, electrostatic discharge, mechanical shock, and vibration are described for complete packaged and pigtailed devices 相似文献
19.
A TE-TM mode converter, useful at either 0.632 or 0.840 μm, has been fabricated on y -cut LiNbO3 by Ti indiffusion with the channel waveguide placed parallel to the z -axis. For TE polarized input, the maximum TM modulation depth is 97 percent at 0.632 μm with a 5-V (pp) drive and 99 percent at 0.840 μm with a 12-V (pp) drive. A similar device operating at 1.3 μm displays 98-percent TE-TM switching at 68 V. Operation involves only coplanar electrodes placed alongside the channel acting on the r 61 electrooptic coefficient. A separately deposited buffer layer is unnecessary. Testing indicates a substantially greater tolerance to electrode misalignment than afforded by similar structures formed in x -cut substrates. Data illustrating immunity to photorefractive drift in the presence of a DC bias voltage is presented for 0.840-μm wavelength operation 相似文献
20.
Double-diffused, lateral n-p-n bipolar transistors were fabricated in a simple CMOS-like process using SIMOX silicon-on-insulator (SOI) substrates. Excellent device characteristics were achieved, with peak h FE=120, BV CEO=10 V, and peak f t=4.5 GHz. The f t versus BV CEO trade-off was studied as a function of n - collector width. f t>25 GHz is predicted for this structure with an improved device layout and optimized basewidth. This process may be easily extended in order to fabricate complementary BJTs in a C-BiCMOS thin-film SOI technology 相似文献