Investigation on gain characteristics in non-degenerate cascaded phase sensitive parametric amplifiers

We theoretically and experimentally show the impact of the ratio between the signal and idler generated from the PIA part on the gain characteristics in the continuous wave (CW) pump non-degenerate cascaded phase-sensitive fiber optical parametric amplifier (PS-FOPA). The results show that the length of highly nonlinear fiber (HNLF) used for generating the idler can cause the variation of power ratio between the idler and signal, which significantly affects the gain characteristics of the PS-FOPA under the small signal gain condition. To obtain high gain, it is better to choose long HNLF to generate idler. In our experiment, 5.5 dB gain and 18 nm bandwidth (on/off gain>10 dBm) in PS-FOPA can be achieved when 300 m-long HNLF instead of 200 m-long HNLF is used in PIA.     

Design and analysis of all-optical up- and down-wavelength converter based on FWM of SOA-MZI for 60 Gbps RZ data signal

In this paper, the design and analysis of the all-optical up- and down-wavelength converter based on four-wave mixing (FWM) effect of semiconductor optical amplifier Mach–Zehnder interferometer (SOA-MZI) have been presented. The return-to-zero (RZ) modulated data signal at a bit rate of 60 Gbps has been evaluated for error-free operation to show the feasibility of proposed system at different pump wavelength. The converted signal power and quality factor are investigated as the function of variable signal power and pump power. The optimized operating input signal power of ?5 dBm with Q-factor of \(\sim \)28 dB for RZ modulated signal by using SOA-MZI structure with enhanced FWM effect. The important contribution of these investigations that it is possible to expand the optical network with limited available channel bandwidth by utilizing the wavelength converter and gives an approach to implement wavelength converter for future hybrid optical access networks.     

Frequency response of a unidirectional-output optical frequencyconversion device with an asymmetrical-κ DBR laser structure

The frequency response of a unidirectional-output optical frequency conversion device is measured. The device has a saturable absorber region within the active region, which acts as an optical gate for converted light. The 3-dB bandwidth of the device with saturable absorber region is measured up to 800 MHz, and is found to be limited by the frequency response of the saturable absorber region. To operate the device faster, lasing mode intensity modulation by input light is attempted by using the device in a laser diode mode. In this case, the electrodes of the saturable absorber and the gain regions are connected electrically, and the saturable absorber region is also biased far above the threshold condition at the same time with the gain region. The 3-dB bandwidth of the device increases to over 10 GHz, and the 10-Gb/s nonreturn-to-zero (NRZ) eye pattern can be observed when the input TM-polarized light intensity is modulated by a 10-Gb/s NRZ pseudorandom signal     

Stabilization of the Gain versus Frequency Characteristics of Parametric Amplifiers at High Input Signal Levels

Decreasing the negative bias voltage of varactor diodes in a parametric amplifier causes the gain versus frequency characteristic of the amplifier to shift to the higher-frequency side, resulting in a so-called "positive slope" at the signal center frequency. The same happens when the pump power is increased or when the signal power is increased, but in the latter case only when the idler circuit load resistance is below a certain value. The slope of the gain characteristic can be partially or completely compensated by detuning the signal-circuit characteristic relative to the gain versus freqnency characteristic in such a way that the latter is located on a certain point of the left or right slope of the signal-circuit chara-teristic, or by resistive loading of the idler circuit. Complete cancellation was achieved in the range from -30 to -20 dBm signal input power by using both methods simultaneously on a practical model of a parametric amplifier operating at a signal center frequency of 3.95 GHz and a pump frequency of 11.76 GHz. The loading of the idler circuit was done by drawing a little rectified diode current. The necessary increase in pump power, in order to maintain the same gain as with both signal and idler circuits tuned to resonance, was less than 3 dB, the increase in noise figure a few tenths of 1 dB from a typical value of approximately 3 dB.     

An Integrated CMOS Front-End for Optical Absolute Rotary Encoders

This paper presents a front-end circuit for optical rotary encoders. The light pulses modulated by the encoder disc are transduced into current signals, which are pre-processed and converted into digital waveforms related to the disc angular position information. The proposed front-end circuit is compensated against temperature drifts. Digitally programmable calibration is provided to account for spreads in impinging light pulse power. Measurement results on integrated prototypes are shown, demonstrating correct operation of the front-end with an optical input power from 0.5 W to 3 W up to a signal frequency of 500 kHz in a temperature range from 0 °C to 80 °C.     

A W-Band Medium Power Amplifier in 90 nm CMOS

A W-band CMOS medium power amplifier (PA) is presented in this letter. The circuit is implemented in 90 nm mixed signal/radio frequency CMOS process. By utilizing balanced architecture, the PA demonstrated a measured maximum small signal gain of 17 dB with 3 dB bandwidth from 91 to 108 GHz. The saturation output power $(P_{rm sat})$ is 12 dBm between 90 and 100 GHz for $V_{rm ds}$ of each transistor at 1.5 V. To our knowledge, this is the highest frequency CMOS PA to date.      

Laser Radar Receiver Channel With Timing Detector Based on Front End Unipolar-to-Bipolar Pulse Shaping

An integrated receiver channel for a pulsed time-of-flight laser range finder is presented based on a timing discrimination principle in which the incoming unipolar detector current pulse is converted to a bipolar pulse at the front end of the receiver channel. Thus no optical or electrical gain control is needed within the dynamic range of the receiver, which according to measurements is 1:3000 with a timing walk error of $pm$55 ps ( $pm$8 mm in distance). The minimum detectable input signal current is about 1.3 $muhbox{A}$ at an SNR of 10 with a bandwidth of 200 MHz. The circuit is realized in a 0.35$ muhbox{m}$ SiGe BiCMOS process and consumes 220 $~$mW of power.      

基于半导体光放大器中交叉偏振调制效应的波长转换器

了改善基于半导体光放大器(SOA)中交叉偏振调制效应(CPM)的波长转换器的转换信号码型效应，对交叉偏振调制一半导体光放大器波长转换器的工作原理进行了分析；通过讨论交叉偏振调制一半导体光放大器波长转换脉冲的上升沿和下降沿的频率啁啾，结合滤波器的透过谱特性，提出了一种利用滤波器的波长正斜率边和波长负斜率边分别对正相转换信号和反相转换信号进行码型优化的方案，并进行了实验验证。在信号码率为10Gb／s的交叉偏振调制一半导体光放大器波长转换实验中，采用光带宽为0．3nm的JDS滤波器优化转换信号的波形，基本消除了转换信号中长“1”码和长“0”码的码型效应，并将正相转换信号和反相转换信号的功率代价分别改善了3dB以上。     

A Design Theory for Wide-Band Parametric Amplifiers

A new exact design theory for a nondegenerate parametric amplifier with double-tuned signal circuit and single-tuned idler circuit is described. If the resistance of the signal circuit, which is neglected in previous papers, is considered, there exists a frequency band in which the amplifier gain is positive. In this paper the band characteristics of the gain are related to this frequency band. Slope parameters of the idler and signal circuits are normalized by the slope parameters which are associated with the diode itself. These normalized slope parameters are used to relate the actual circuit and gain-bandwidth characteristics. The slope parameter of the external signal resonator is related to the negative slope parameter of the diode, and bounds on this ratio are given over which stable amplification is possible. A design table which gives the coupling ratio and slope parameter of the external signal resonator is derived by computer calculation. Experiments were made at 19 GHz. Positive-gain bandwidth was around 4.0 GHz, and flat bandwidth at 10-dB gain was 2.4 GHz. The ratio of these bandwidths coincided with the theory.     

60 GHz OCS mm-wave generation for ROF system based on saturated parametric amplification effect in HNLF

A novel approach to generate 60 GHz optical carrier suppression (OCS) millimeter-wave (mm-wave) signal based on the saturated optical parametric amplification (OPA) effect in high non-linear fiber (HNLF) is investigated. In the proposed system, the OPA effect occurs when the signal and pump with 30 GHz frequency interval are set into the high non-linear fiber. By controlling the length of HNLF, OPA effect saturates, and the pump power is delivered in a large extent to the signal and idler light, so a 60 GHz OCS mm-wave is generated. The system does not need high-speed external modulator, high-frequency vibration source or narrow-band filter, which greatly reduces the cost and improves the stability of the radio over fiber (ROF) system. Results show that the 10 Gb/s downstream signal can be transmitted with negligible power penalty.     

基于MBER的联合预编码与空时编码GFDM功率分配策略

为改善频率选择性衰落信道上广义频分复用（GFDM）系统的误比特率和频带利用率性能,基于最小误比特率（MBER）准则,提出一种联合预编码和空时编码（STC）的 GFDM 系统及其相应的功率分配策略,可将该功率分配策略的优化目标由MBER转化为最小化其噪声增强因子,并推导了联合预编码与空时编码 GFDM 系统的功率分配、误比特率和频带利用率性能解析表达式。数值计算和仿真结果表明,与预编码STC-GFDM系统相比,基于MBER准则的预编码STC-GFDM系统的误码性能在误比特率为10^-3时改善约0.4 dB,频带利用率性能在信噪比为12 dB时提高约0.24 bit/(s·Hz)。     

Tunable wavelength conversion in a semiconductor-fiber ring laser

A tunable wavelength converter is demonstrated using highly nondegenerate four-wave mixing in a semiconductor-fiber ring cavity with no external pump light and low input signal power requirements. This device allows continuous tuning of both pump and converted wavelengths over the semiconductor optical amplifier gain bandwidth. Results for 11.8-nm down- and 6.9-nm up-wavelength conversion with input signal power as low as -10 dBm have been obtained at 1 Gb/s with less than 1.6-dB power penalty     

基于SOA四波混频效应的慢光特性研究

根据行波SOA的四波混频效应,讨论了不同参数条件下的慢光时延特性。采用SOA分段模型,定量分析了光时延量与偏置电流、频率失谐、泵浦光功率的关系,以及泵浦光功率、载流子寿命的改变对工作带宽的影响。结果表明:可以通过调节频率失谐、偏置电流等参数对光时延量进行控制,增加泵浦光功率或抑制载流子寿命均可提高工作带宽。     

A New Low Voltage CMOS Transconductor for VHF Filtering Applications

In this paper, a new differential input CMOS transconductor circuit for VHF filtering application is introduced. The new circuit has a very high frequency bandwidth, large linear differential mode input range and good common mode signal rejection capability. Using 0.35 m CMOS technology with 3 V power supply, the transconductor has a ±0.9 V linear differential input range with a –54 dB total harmonic distortion (THD) and more than 1 GHz – 3 dB bandwidth. The large signal DC analysis and small signal ac analysis derived by compact equations are in line with SpectreS simulation. A 3rd order elliptic low pass g _m-C filter with a cutoff frequency of 150 MHz is demonstrated as an application of the new transconductor.     

Millimeter Wave Varistor Mode Schottky Diode Frequency Doubler in CMOS

The first mm-wave varistor mode Schottky diode frequency doubler fabricated in CMOS is demonstrated. The doubler exhibits 14 dB conversion loss, $-11~{rm dBm}$ output power at 132 GHz and 6 GHz 3-dB output bandwidth from 128 to 134 GHz. The input matching is better than $-10~{rm dB}$ and the rejection of fundamental signal at output is greater than 14 dB from 62 to 70 GHz.      

70-MHz IF 10-MHz bandwidth bandpass \Upsigma\Updelta modulator for WCDMA applications

A MASH bandpass $\Upsigma\Updelta$ modulator for wide-band code division multiple access (WCDMA) applications is presented. The signal bandwidth of the proposed modulator is 10?MHz centered around an intermediate frequency (IF) of 70.5?MHz. Two two-path second-order bandpass $\Upsigma\Updelta$ modulators make the MASH architecture, which realizes a noise transfer function with four couples of complex conjugate zeros. The proposed circuit, fabricated with a 0.18???m CMOS technology, uses a sampling frequency of 180?MHz to obtain a resolution of about 12?bits in the 10?MHz bandwidth around the IF. The measured modulator power consumption is 95?mW with a supply voltage of 1.8?V. The achieved figure-of-merit (FoM _BP ) is 0.37?pJ/conversion-level.     

18-GHz Paramps with Triple-Tuned Gain Characteristics for Both Room- and Liquid-Helium-Temperature Operation

The design and experimental performance of a wide-band K-band parametric amplifier (paramp) for the experimental domestic satellite communication earth station are described. An optimum idler frequency for a minimum noise temperature is derived taking into account the varactor diode skin effect. Wide-band paramps with a double-tuned signal circuit are discussed and it is shown that triple-tuned gain characteristics are realizable with this configuration. Finally, an 18-GHz paramp is described, which can be operated from room- to liquid-helium (LHe) temperature, only requiring adjustment of pumping power and bias voltage and using lithium ferrite circulators. Triple-tuned gain characteristics with a bandwidth of 1300 MHz at a gain of 10 dB are obtained using a miniature pill prong packaged varactor.     

Maximum Bandwidth Performance of Non- degenerate Parametric Amplifier with Single-Tuned Idler Circuit

The single-tuned bandwidth and limiting flat bandwidth of a nondegenerate reflection-type diode parametric amplifier is calculated. The amplifier has a broad-banding filter structure in the signal circuit and a single-tuned idler circuit. An experimental low-noise, wide-band Z-band amplifier is described, and measurement results are presented. The amplifier has a triple-tuned signal circuit and a single-tuned idler circuit and is pumped at 11.3 Gc. A nearly flat bandwidth of 23 per cent at 7 db gain and an effective input noise temperature of 70/spl deg/K at room temperature ambient and of 29/spl deg/K at liquid nitrogen (77/spl deg/K) ambient has been obtained.     

A CMOS Code-Modulated Path-Sharing Multi-Antenna Receiver Front-End

This paper presents the design and implementation of a novel multi-antenna receiver front-end, which is capable of accommodating various multi-antenna schemes including spatial multiplexing (SM), spatial diversity (SD), and beamforming (BF). The use of orthogonal code-modulation at the RF stage of multi-antenna signal paths enables linear combination of all mutually orthogonal code-modulated RF received signals. The combined signal is then fed to a single RF/baseband/ADC chain. In the digital domain, all antenna signals are fully recovered using matched filters. Primary advantages of this architecture include a significant reduction in area and power consumption. Moreover, the path-sharing of multiple RF signals mitigates the issues of LO routing/distribution and cross-talk between receive chains. System-level analyses of variable gain/dynamic range, bandwidth/area/power trade-off, and interferers are presented. Designed for the 5-GHz frequency and fabricated in 0.18 $mu$m CMOS, the 76 mW 2.3 mm$^{2}$ two-antenna receiver front-end prototype achieves a 10$^{-2}$ symbol error rate (SER) at 64, 77, and 78 dBm of input power for SM, SD, and BF, respectively, while providing 21–85 dB gain, 6.2 dB NF, and 10.6 dBm IIP3.      

Broad-band 88% efficient two-pump fiber optical parametric amplifier

We demonstrate, for the first time to the best of our knowledge, a highly efficient continuous-wave two-pump fiber optical parametric amplifier. We used a total pump power of /spl sim/280mW in a 14-km-long fiber and obtained 88% power transfer from pumps to signal and idler over 25-nm bandwidth centered at 1568 nm.