Rayleigh scattering influence on performance of 10 Gb/s opticalreceiver with Er-doped optical fiber preamplifier

The achievement of -30.8 dBm (630 photon/bit) receiver sensitivity at 10 Gb/s, with an Er³⁺-doped optical fiber preamplifier, is discussed. This is an 8.3-dB sensitivity improvement over the avalanche-photodiode/FET receiver. Power penalties caused by a noise increase due to Rayleigh backscattering by the transmission optical fiber have been evaluated. Approximately -30-dB Rayleigh scattering from a 20-km optical fiber resulted in a 3.5-dB power penalty for a 25-dB-gain optical amplifier     

Noise performance of erbium-doped fiber amplifier pumped at 1.49μm, and application to signal preamplification at 1.8 Gbit/s

Direct measurements of the noise figure of an erbium-doped fiber amplifier are described. With an amplifier gain as high as 36 dB, a noise figure as low as 4.1 dB was measured. Noise figures remained below 6 dB for signal wavelengths within the high gain (G>20 dB) region of the amplifier. An optical receiver sensitivity of -43 dBm at 1.8 Gb/s, corresponding to 215 photons/b, was achieved using the fiber amplifier as an optical preamplifier for a direct detection receiver     

Stimulated Raman amplification of 1.6-μm-band pulsed light inoptical fibers

A synchronous Raman fiber amplifier is proposed which is pumped at a wavelength around 1.55 μm by output pulses from an erbium-doped fiber amplifier. This arrangement achieves an output optical peak power exceeding 200 mW and a 3-dB net gain bandwidth of 33 nm around 1.66 μm. The Raman fiber amplifier is useful for 1.6-μm-band OTDR as it can be used in live maintenance of optical transmission networks     

High-gain mode-adapted semiconductor optical amplifier with12.4-dBm saturation output power at 1550 nm

A mode-adapted semiconductor optical amplifier (SOA) has been fabricated and packaged. At the gain peak, 1500 nm, the fiber to fiber gain was measured to be 32.5 dB. Statistics for eight packaged devices indicate that a fiber-to-fiber gain of 26.3 dB ± 1.3 dB and a saturation output power of 12.4 dBm ± 0.4 dBm are typical at a bias of 500 mA for λ = 1550 nm. Polarization sensitivity at 1550 nm was measured to be 1.1 dB ± 0.4 dB and the transverse electric (TE) polarization state noise figure (NF) was determined to be 7.0 dB ± 0.5 dB. The coupling loss was 1.3 dB ± 0.1 dB per facet. This SOA, with a 1.3-nm filter, was used as an optical preamplifier in a 10-Gb/s return-to-zero (RZ) system testbed with a pseudorandom binary sequence (PRBS) of 2³¹ -1. A 14.5-dB improvement in receiver sensitivity was observed at a bit error rate (BER) of 10^-11     

Sensitivity improvement of a 2 Gb/s quadrature phase shift keyedsubcarrier multiplexed system by use of an optical preamplifier

A traveling wave semiconductor optical amplifier is used as a receiver preamplifier in a quadrature-phase-shift-keyed subcarrier multiplexed system. The intensity-modulated signal from a 1509-m distributed feedback laser bears two 1-Gb/s data signals on a 5-GHz subcarrier. The receiver preamplifier yields a 9.2-dB sensitivity improvement to -29.2 dBm. The system noise sources are measured. Theoretical and measured bit error rates versus received power are presented     

Gain-shifted dual-wavelength-pumped thulium-doped fiber amplifierfor WDM signals in the 1.48-1.51-μm wavelength region

We constructed a gain-shifted dual-wavelength-pumped (1.05/1.56 μm) thulium doped fiber amplifier (TDFA) for wavelength-division-multiplexing (WDM) signals in the 1.48-1.51-μm, wavelength region. We obtained a gain of larger than 20 dB and a noise figure of less than 7 dB in the range from 1478 to 1505 nm. Amplifier saturated output power was +20.1 dBm with an optical-to-optical conversion efficiency of 9.1% for 12-channel WDM signals. We also obtained a successful bit error rate performance for signals modulated at 10 Gb/s when the gain-shifted TDFA was used in an optical preamplifier configuration. These results confirm the feasibility of using the gain-shifted TDFA as both a booster and an optical preamplifier in WDM networks     

应用于10Gb/s光接收机的全差分CMOS跨阻前置电路设计

设计了一种的低成本、低功耗的10 Gb/s光接收机全差跨阻前置放大电路。该电路由跨阻放大器、限幅放大器和输出缓冲电路组成,其可将微弱的光电流信号转换为摆幅为400 mVpp的差分电压信号。该全差分前置放大电路采用0.18 m CMOS工艺进行设计,当光电二极管电容为250 fF时,该光接收机前置放大电路的跨阻增益为92 dB,-3 dB带宽为7.9 GHz,平均等效输入噪声电流谱密度约为23 pA/(0~8 GHz)。该电路采用电源电压为1.8 V时,跨阻放大器功耗为28 mW,限幅放大器功耗为80 mW,输出缓冲器功耗为40 mW,其芯片面积为800 m1 700 m。     

Characteristics of a semiconductor laser pumped brillouin amplifier with electronically controlled bandwidth

We demonstrate the operation of a semiconductor laser pumped fiber Brillouin amplifier. An optical gain of 5.5 dB/mW of pump power is obtained. The 15-MHz intrinsic bandwidth of the amplifier was extended more than one order of magnitude by adding frequency modulation to the pump laser. Bit-error-rate receiver sensitivity measurements with an in-line Brillouin amplifier demonstrate a 16-dB improvement in the system gain at 10 Mbit/s and a 8.5-dB improvement at 90 Mbit/s. Noise calculations show that the amplifier has an excess noise factor of 50-500 depending on the amplifier length and pump power.     

Properties of fiber Raman amplifiers and their applicability todigital optical communication systems

Bit error rate performances of fiber Raman amplifiers both as booster amplifiers and as detection preamplifiers are studied in intensity modulation/direct detection optical communication systems. It is theoretically shown that, in the booster amplifier application, receiver sensitivity degradation due to amplification can be made less than 0.2 dB for signal-to-noise power ratio larger than 20 dB, and thus an allowable transmission line loss can be increased approximately by the value of Raman gain. For detection preamplifier use, receiver sensitivities in the Raman preamplifier system are numerically calculated in terms of minimum detectable signal power at 100-Mbit/s and 2-Gbit/s bit rates. In both bit rates, it is shown that, for a Raman gain greater than 20 dB, minimum detectable signal power can be improved by more than 15 dB over the conventional detection level without Raman amplification. Preliminary experiments are carried out using a 1.32-μm Nd:YAG laser and a 1.4-μm laser diode as pump and signal light sources, respectively. The experimental results are in good agreement with theoretical estimations     

1.55-μm polarization-insensitive optical amplifier withstrain-balanced superlattice active layer

A polarization insensitive (sensitivity <1 dB) GaInAs-GaInAsP semiconductor optical amplifier has been realized at 1.55 μm. The active layer consists of a strain-balanced superlattice structure. Gain polarization insensitivity on a large bandwidth (60 nm) together with a 22.5-dB signal gain and a 11-dBm polarization-insensitive saturation output power are obtained     

REAP: recycled erbium amplifier pump

We report a novel erbium doped fiber preamplifier design with a combination of high gain (>40 dB) and low noise figure (3 dB) at 1556 nm for 80 mW of 980 nm pump power. The co-directional single pumped amplifier employs a composite two stage arrangement in which the second stage is pumped with recycled pump not used in the first stage. In addition, we contrast the amplifier performance trade-offs with the insertions of an isolator or a band pass filter or both in between the two amplifier sections. Finally, we demonstrate a receiver sensitivity of -37 dBm (156 photons/bit) with a 10 Gb/s optical preamplifier regenerator     

Gain characteristics of an Er3+-doped multicomponentglass single-mode optical fiber

Experimental results on gain characteristics of an Er³⁺-doped multicomponent glass single-mode optical-fiber amplifier are reported. This amplifier shows a gain spectrum with twin gain peaks of 1.535 and 1.543 μm, providing a broadened gain bandwidth. The apparent 6-dB gain bandwidth is 12 nm. Furthermore, the signal gain of 17 dB and 15-mW pump power is realized at a signal wavelength of 1.536 μm, and a signal gain coefficient of 1.4 dB/mW is achieved     

5-GHz CMOS radio transceiver front-end chipset

Incorporating the direct-conversion architecture, a 5-GHz band radio transceiver front end chipset for wireless LAN applications is implemented in a 0.25-μm CMOS technology. The 4-mm² 5.25-GHz receiver IC contains a low noise amplifier with 2.5-dB noise figure (NF) and 16-dB power gain, a receive mixer with 12.0 dB single sideband NF, 13.7-dB voltage gain, and -5 dBm input 1-dB compression point. The 2.7-mm² transmitter IC achieves an output 1-dB compression of -2.5 dBm at 5.7 GHz with 33.4-dB (image) sideband rejection by using an integrated quadrature voltage-controlled oscillator. Operating from a 3-V supply, the power consumptions for the receiver and transmitter are 114 and 120 mW, respectively     

FM microwave multiplexed broad-band distribution systems using Er3+ fiber amplifiers and preamplifiers

The use of an Er³⁺ fiber preamplifier for microwave multiplexed systems and the use of an inline Er³⁺ amplifier in microwave multiplexed systems for signal distribution are reported. The improvement in receiver sensitivity as a preamplifier, without optical filtering, was 9 dB. No power penalty due to amplified spontaneous emission was found when the amplifier was used in a 30-channel signal distribution system     

InGaAs/InGaAsP MQW optical amplifier integrated withgrating-assisted vertical-coupler noise filter

A photonic integrated circuit with an InGaAs/InGaAsP multiple-quantum-well (MQW) traveling-wave optical amplifier and a grating-assisted vertical-coupler filter as a noise filter have been demonstrated. A fiber-to-amplifier/filter gain of ~0.5 dB and a 3-dB filter bandwidth (FWHM) of ~70 Å at 1.56 μm filter center wavelength have been achieved. This photonic circuit is potentially suitable as a building-block for preamplifier lightwave receivers or high-gain, high-power optical amplifiers which are essential for optical communication systems and lightwave networks     

Bipolar monolithic amplifiers for a gigabit optical repeater

Main amplifier, AGC amplifier, and preamplifier ICs have been designed and fabricated using an advanced silicon bipolar process to provide the required characteristics of repeater circuits for a gigabit optical fiber transmission system. The bipolar technology used involved a separation width of 0.3 /spl mu/m between the emitter and the base electrode. New circuit techniques were also used. The differential type main amplifier has a peaking function which can be varied widely by means of DC voltage supplied at the outside IC terminal. A bandwidth which can be varied to about three times the value for a nonpeaking amplifier is easily obtained. The gain and maximum 3-dB down bandwidth were 4 dB and 4 GHz, respectively. The main feature of the AGC amplifier is that the diodes are connected to the emitters of the differential transistor pair to improve the linearity. The maximum gain and 3-dB down bandwidth were 15 dB and 1.4 GHz, respectively, and a dynamic range of 25 dB was obtained. The preamplifier has a shunt-series feedback configuration. Furthermore, a gain and 3-dB down bandwidth of 22 dB and 2 GHz, respectively, were achieved with an optimum circuit design. The noise figure obtained was 3.5 dB.     

Vertical-cavity amplifying modulator at 1.3 μm

The modulation/switching properties of a vertical-cavity semiconductor optical amplifier operating at 1.3 μm wavelength are investigated. The device was optically pumped and operated in reflection mode. A 150-mV (100 mA) modulation of the drive to the pump source produced a 7-dB modulation of the pump power, which produced a 35-dB modulation in the output signal. The maximum extinction ratio was 35 dB, and limited by device heating. Frequency response measurements revealed a modulation bandwidth of 1.8 GHz when the amplifier was saturated. This enabled 2.5-Gb/s modulation of a -10 dBm input signal with 5.5-dB fiber-to-fiber gain     

Er3+-doped fiber amplifier pumped by 0.98 μm laserdiodes

The performance of an Er³⁺-doped fiber amplifier pumped by 0.98 μm InGaAs laser diodes (LDs) is reported. By using a fiber with low Er³⁺ content and optimizing the fiber length, a maximum signal gain of 37.8 dB at 30-mW pump power was realized at a signal wavelength of 1.536 μm. A maximum gain coefficient of 1.9 dB/mW at 14 mW pump power was achieved. It was found that the fiber amplifier pumped by the 0.98-μm LDs is twice as efficient as that pumped by 1.48-μm LDs, from the viewpoint of both required fiber length and the attained gain     

GaAs Monolithic MIC's for Direct Broadcast Satellite Receivers

A 12-GHz low-noise amplifier (LNA), a 1-GHz IF amplifier (IFA), and an 11-GHz dielectric resonator oscillator (DRO) have been developed for DBS home receiver applications by using GaAs monolithic microwave integrated circuit (MMIC) technology. Each MMIC chip contains FET's as active elements and self-biasing source resistors and bypass capacitors for a single power supply operation. It also contairns dc-block and RF-bypass capacitors. The three-stage LNA exhibits a 3.4-dB noise figure and a 19.5-dB gain over 11.7-12.2 GHz. The negative-feedback-type three-stage IFA shows a 3.9-dB noise figure and a 23-dB gain over 0.5-1.5 GHz. The DRO gives 10.mW output power at 10.67 GHz, with a frequency stability of 1.5 MHz over a temperature range from -40-80°C. A direct broadcast satellite (DBS) receiver incorporating these MMIC's exhibits an overafl noise figure of /spl les/ 4.0 dB for frequencies from 11.7-12.2 GHz.     

A wide-dynamic-range, high-transimpedance Si bipolar preamplifierIC for 10-Gb/s optical fiber links

A wide-dynamic-range, high-transimpedance preamplifier IC for 10-Gb/s optical fiber links was developed using a 0.3-μm Si bipolar process. The preamplifier with a limiting amplifier enables a wide dynamic range from 16 μApp to 2.5 mApp and a high transimpedance of 1 kΩ (2 kΩ in the differential output mode). Moreover, careful circuit design achieves a transimpedance fluctuation of 0.5 dBR and an average equivalent input noise current density of 12 pA/√Hz. This preamplifier IC has the highest transimpedance of any Si bipolar preamplifier for 10-Gb/s operation. Thus, the preamplifier is suitable for 10-Gb/s short-haul optical fiber links and can be used to provide a low-cost system