A Ferrimagnetically-Tuned Parametric Amplifier

A parametric amplifier can normally be tuned only over relatively restricted frequency ranges. One of the basic reasons for this tuning difficulty is that more than one frequency range is of importance for, in addition to the signal frequency, a pump frequency and one or more sum or difference frequencies must be considered. In this paper a tunable negative-resistance parametric amplifier is described which uses ferrimagnetically-tuned signal and idler circuits, together with a fixed-frequency pump source. This amplifier is unique in two respects. One is that the amplifier is electrically tuned through the use of yttrium iron garnet (YIG) resonators. Secondly, useful low-noise performance has been achieved over a tuning range of almost one octave, this amplifier thus successfully demonstrates that the technique of magnetic tuning with YIG resonators can be applied to a device as complex as a parametric amplifier in much the same manner as it has been applied in the past to microwave band-pass and band-stop filters.     

A Unilateral Parametric Amplifier

A theoretical investigation of a unilateral parametric amplifier using two varactor diodes indicates an improvement of unilateral stability over already existing types. A circuit is suggested which uses lower sideband idler energy for achieving forward gain and upper side-band energy to obtain substantial reverse loss. The phases of the applied signals and of the pump at the two varactors have to be 90/spl deg/ out of phase to achieve unilateral operation. Numerical evaluation of the theoretical results for a signal frequency at 4.0 GHz and a pump frequency at 12.0 GHz, assuming a diode junction capacitance of C/sub j/ = 0.4 pF and a bulk resistance of R/sub s/ = 2/spl Omega/ was done for several pump power levels. For 14 dB maximum forward gain, the 3 dB bandwidth of the gain versus frequency characteristic of the unilateral amplifier is about 18 percent smaller than that of the reflection type amplifier. The maximum reverse loss for these conditions is 7.3 dB. For lower forward gain the backward loss increases relatively until for very low gain values (about 1 dB) the amplifier is unconditionally stable, i.e., the backward loss is larger than the forward gain. The theoretical noise figure is about 1.95 dB at signal center frequency for 14 dB forward gain and, for /spl plusmn/80 MHz from the center frequency, only 0.1 dB higher than for the reflection type amplifier.     

A VHF Hybrid Parametric Amplifier

This paper describes the design and performance of a VHF hybrid parametric amplifier at 30 MHz. A noise temperature of 18 K coupled with a 6-dB gain and 6-MHz bandwidth is obtained.     

A Nondegenerate Traveling-Wave Parametric Amplifier

The traveliig-wave parametric amplifiers reported to date are not sufficiently competitive to ensure their use in advanced RADAR systems. The major hindrance is the relatively high-RADAR noise figure which is due to the fact that the signal and idler frequencies are about equal; i.e., the amplifier is degenerate. Initial experiments directed toward obtaining a nondegenerate microwave traveling-wave parametric amplifier are reported in this paper. A promising circuit has been developed and an S-band nondegenerate amplifier has been built and tested. In the first part of the paper the circuit is described and the experimental results are given. The second part of the paper describes procedures which have proved useful in the development of the circuit and which should also prove useful in future investigations.     

UHF Backward-Wave Parametric Amplifier

This paper describes a breadboard model of a UHF varactor diode backward-wave parametric amplifier that can be electronically tuned over an octave tuning range (250-500 Mc). It operates in a mode that has a relatively constant idler frequency; however, it uses two forward-wave transmission lines in contrast to the backward-wave transmission line requirement previously reported. A theoretical discussion on the design considerations of this mode is presented and applied to the UHF model. Measurements taken in the conventional mode of operation (output frequency equal to the input frequency) yielded voltage gain bandwidth products in excess of 100 Mc and over-all effective receiver noise temperatures of less than 140/spl deg/k. Detailed measurements in the mode where the constant idler frequency is used as the output were not taken because directional filters and circulators, which are necessary in this mode, were not available.     

Parametric Amplifier Noise Analysis

The effect of a different value of series resistance associated with the varactor in its imbedding at each of the important frequencies present in a one-port parametric amplifier is analyzed. The modified equations for effective noise temperature, amplifier gain and pump power required thus obtained are compared to experimental values measured on a 4.8 Gc/s parametric amplifier. Finally a simple and precise method for adjusting the amplifier to get close correlation between the measured varactor parameters using Kurokawa's method at signal idler, and pump frequencies and the overall amplifier performance is presented.     

The Hybrid Parametric Amplifier

This paper calculates the gain and noise performance of a new version of the parametric arnplifier in which the signal circuit is part of an artificial transmission line while the idler circuit is resonant. A particularly useful property of this type of parametric amplifier is absence of oscillation with increasing pump power.     

An Environmentalized Low-Noise Parametric Amplifier

A 14-oz low-noise, X-band parametric amplifier has been developed for an airborne environment (-55 to +71/slp deg/C). This unit exhibits a 1.8-dB noise figure at 10 GHz and, at 18-dB peak gain, a 3-dB single-tuned bandwidth of 230 MHz that is electronically tunable over 700 MHz. A 1-dB gain compression occurs at -27-dBm input power. Performance is achieved through use of unique upper sideband terminated circuitry and a new low-parasitic, hermetic varactor package.     

Broad-Band Cavity-Type Parametric Amplifier Design

This paper tells how maximum bandwidth can be obtained from a nondegenerate parametric amplifier which utilizes a circulator. Expressions are derived for the gain bandwidth product and maximum possible gain bandwidth product. It is then shown how the Q of the cavities used for the signal and idler circuits may be kept at a minimum without degrading the noise performance of the amplifier. It is shown that best performance results when the TEM mode is used in coax, or, if waveguide is used, when the operating frequency is far away from the waveguide cutoff frequency. The diode used should have as high a self-resonant frequency as possible and the line admittance should be approximately the diode susceptance. Using a diode with a self-resonant frequency at the idler frequency will be seen to give optimum performance. This paper also discusses double tuning the signal circuit to achieve broader bandwidths. In this case, the addition of the second tuned circuit will be seen to give much broader bandwidths than one would expect from conventional filter theory. Two sample amplifiers are considered and their bandwidths calculated. The effect of double tuning one of the amplifiers is then considered.     

Scalable Multicasting in One-Pump Parametric Amplifier

We report the experimental demonstration of all-optical wavelength multicasting of OC-768 (40 Gbps) channel using a single-pass, pump modulated parametric amplifier. The performances of 1-to-20 and 1-to-40 multicasting with excellent signal fidelity were observed. The impairment mechanisms were identified from cascaded filtering, linear and nonlinear crosstalk. It is shown that the parametric amplifier offers a wide range of operation characterized by minimal multicast penalty. We show that all multicast channels have an error free performance with Q factors well above the forward error correction (FEC) limit within the designed operating range.      

Read-Type Varactors for Parametric Amplifier Applications

The use of Read-type HI-LO doping profiles in varactors for pararnetric amplifier applications is shown to result in improved performance over conventional structures. Optimal diode doping Ievels layer thicknesses, and pump drive levels are derived which give specified frequency performance while minimizing pump power requirements, minimizing noise, maximizing dynamic range, and reducing amplifier sensitivity to pump power fluctuations. The optimum device design is based on environmental Iimitations such as pump power, circuit losses and impedance Ievels and the unavoidable diode series resistance level. Design examples are given for 10- and 100-GHZ parametric amplifiers.     

An 18-GHz Double-Tuned Parametric Amplifier

A K/sub u/-band nondegenerate parametric amplifier using a single-packaged GaAs varactor diode is described. A very simple structure of the single-tuned amplifier with a new type of idler choke is employed to obtain a large voltage-gain bandwidth product and a low noise temperature. The double-tuned operation exhibits a nearly flat bandwidth of 550 MHz at a 20-dB gain and a noise temperature of 280/spl deg/K at room-temperature ambience.     

A Compact and Robust Regenerative Amplifier Pump Source for High Repetition Rate Terahertz Parametric Amplifier

In this paper we report a compact and robust regenerative amplifier developed as the pump laser for a high repetition rate terahertz parametric amplifier.With properly chosen pump source and carefully designed cavity,Nd∶YVO4 crystal, and laser beam collimator, a maximum output pulse energy of 480 μJ has been achieved at the repetition rate of 10 k Hz.The output laser has a nearly Gaussian transverse profile and a narrow bandwidth of 0.2 nm.Long-term monitoring shows an root mean square power flu...     

A Low-Noise X-Band Parametric Amplifier Using a Silicon Mesa Diode

This paper summarizes a cooperative effort to develop silicon mesa variable-capacitance diodes and to evaluate their potential for achieving low-noise amplification in the high microwave frequency range. Cutoff frequencies of about 70 kMc at zero-bias voltage (corresponding to 140 kMc at maximum reverse bias voltage) with a total permissible voltage swing in excess of 5 volts have been obtained. A versatile degenerate X-band parametric amplifier was developed which, when used in conjunction with these silicon mesa diodes, achieved a radiometer noise temperature of 130°K at 8.5 kMc with a 50-Mc bandwidth at 17-db gain. The measured performance of the diode (figure of merit) is compared with the first-order theory in an operating radar system. The over-all performance of the amplifier improved the observed system sensitivity by 6 db.     

Balanced Parametric Amplifier of the MM Range

Results of research of balanced circuit of noncooled input parametric amplifier for 60 – 65 GHz band are given in this work. Elektrodynamics characteristics of oscillatory system in which there were used waveguide converters of H ₁₀-wave into H ₂₀ based on angle inhomogeneous are studied. The experimental results of research of amplifier models that based on BSD without package are shown. Amplification factor is 10–15 dB; noise temperature is 400 - 500 ⁰K.     

Theoretical Limitations to Ferromagnetic Parametric Amplifier Performance

It has been commonly expected that improved operation of the ferrite parametric amplfier could be obtained by use of materials of narrower resonance linewidth, Delta H. This parameter is critical in determining the pumping power (P/sub p/) required for operation of the device. Also of importance, however, is the limitation of device properties determined by the dependence on Delta H of the instability threshold of the spin-wave system. Considering this limitation, the maximum voltage gain-fractional bandwidth product (g/sub v/Delta omega/omega/sub 1/) has been determined as a function of other device parameters, and typical values calculated for several modes of operation. In the electromagnetic mode, for example, there is an optimum Delta H which yields maximum g/sub v/Delta omega/omega/sub 1/) at a given pumping power. It is also shown that a minimum filling factor, also a function of Delta H for some types of operation, is required to reach the oscillation threshold even in the unloaded device.     

Some Limitations on Parametric Amplifier Noise Performance

Now that the precursory period following the solid-state parametric amplifier invention has given way to an era of determined effort to reduce to practice some of the early, optimistic predictions, practical limitations setting an upper bound to the performance of this ingenious communications device have become apparent. In this paper, two such limitations are discussed: First, for a given diode Q and junction geometry, there exists a noninfinite idler frequency, which determines the lowest radar noise temperature. Second, because of its extreme noisiness the reverse-break-down current limits the maximum capacitance swing at both extremes and consequently the minimum noise performance. It is suggested that in certain cases refrigeration may be a partial remedy to both limitations.     

飞秒激光行波泵浦BBO晶体光参量放大

采用飞秒钛宝石激光放大器二次谐波为泵浦源，行波泵浦ＢＢＯ晶体光参量放大器，获得了可调谐输出（０．４４～２．６μｍ），最大输出能量约４０μＪ／脉冲，测量了参量激光的调谐特性、能量分布和线宽，理论与实验符合较好。     

Broad-Band Parametric Amplifier Design (Correspondence)

A computerized optimization technique is employed to provide design values for broad-band parametric amplifiers. Some results of the procedure are presented.     

光纤参量放大器增益带宽拓宽技术

光纤参量放大器在当今高速WDM光纤通信系统中有广泛的应用前景，宽带宽是其主要特性之一，本文在分析诸如光纤的色散平坦斜率、零色散波长及双折射因素对光纤参量放大器增益带宽的影响的基础上，论述了拓宽增益带宽的几种方法和设计技术。