Optical Preamplifier Research Articles

Performance comparison of analogue inter‐satellite microwave photonics link using intensity modulation with direct detection and phase modulation with interferometric detection

The performance of optical inter-satellite communications using microwave photonics technologies employing intensity modulation with direct detection (IMDD) and phase modulation (PM) with interferometric detection are investigated and demonstrated with a numerical example. The theoretical model considering the saturated gain and amplifier spontaneous emission noise of optical booster amplifier and optical preamplifier is constructed for both architectures. Furthermore, the authors compare the performance of PM with interferometric detection to optimum biased IMDD in terms of radio frequency (RF) gain, RF noise figure and compression dynamic range (CDR). The numerical results show that the PM with interferometric detection can achieve better RF gain, RF noise figure and CDR than the optimum biased IMDD link as the laser output power is lower than 14.34, 12.45 and 4.2 dBm, respectively.

Integrated SOA-PIN Detector for High-Speed Short Reach Applications

Emergence of new applications like cloud computing, video on demand or deployment of high-speed cellular network lead to an increasing demand of high-speed short reach transmission for access network or datacenter. Due to the low sensitivity of PIN receiver and the lack of APD above 10 Gb/s, optical preamplification is a promising concept for high-speed receiver. We demonstrate an SOA-PIN/TIA receiver module which integrates an SOA-PIN photonic circuit and a TIA. This receiver has a large responsivity of 44 A/W, a polarization dependence below 2 dB, a low noise figure of 8.5 dB and a large 3-dB bandwidth of 35 GHz. Our new developed receiver achieved in NRZ a record sensitivity of -23 and -21 dBm at 25 and 40 Gb/s, respectively.

Impact of channel-spacing on next 400 Gb/s Ethernet 40-km PMD based on [formula omitted] WDM architecture

The impact of fiber dispersion, system non-linearities and their interaction when varying the channel-spacing value, ranging from 200 to 800GHz, on the performance of a WDM 16×25Gb/s architecture that has been proposed as next 400Gb/s Ethernet (400GbE) 40-km physical medium dependent (PMD) sublayer is numerically analyzed. It is shown through calculations of the Quality Factor that the gain modulation nonlinearity of the semiconductor optical pre-amplifier is the main phenomenon that degrades the system performance. Moreover, it is demonstrated that its impact becomes dependent on the channel-spacing of the WDM plan, provided that the chromatic dispersion of the fiber is enough to vary the bit-correlation level among channels at the pre-amplifier input. Despite the considerable channel count, the effect of carrier heating-induced four wave mixing (FWM) is found to be rather modest, while the impact of carrier density pulsation-induced FWM and fiber non-linear response resulted to be negligible. With respect to the analyzed phenomena, a wide channel plan, only limited by the gain bandwidth, should be preferred for the 400 GbE implementation, especially if a nanostructured, broad-bandwidth, SOA can be afforded.

디지털 전송 시스템을 위한 광 수신시스템에 관한 연구

광시스템에서 신호와 부가적인 잡음의 통계적인 특성에 대해 다양한 방법으로 평가하는 것은 시스템의 성능 최적화를 위해 필수적인데, 본 논문에서는 스펙트럼분할된 광시스템의 성능해석에서 수신부에 광전치증폭기를 포함시켜 수신된 신호 비트에 대한 에러한계 즉, 비트에러률을 유지하기 위해 필요한 평균광전력을 비트당 포함되는 광자의 수로 나타낸다. 본 논문에서는 신호가 디지털 형태를 띄는 경우 수신기의 감도를 계산하는 방안에 대하여 계산을 수행하였다. 이를 통해 일반 강도변조된 신호의 전송시와 디지털 신호의 전송시에 필요한 광전력의 비교를 보였다. 그림 3에서 보인 것처럼 디지털 신호 전송 시스템이 일반 강도변조된 신호의 전송 시에 비해 최소 10dB 정도 개선이 됨을 확인할 수 있었다. In optical system, the signal and additive noise for statistical properties of a variety of ways to evaluate the performance of the system is essential for the optimization. In this paper, performance analysis of spectrum-sliced optical system in the optical pre-amplifier in the receiver the received signal by including the error limits for the bit that is, the bit error rate (BER: Bit Error Rate) required to maintain the average optical power represents the number of photons per bit is included in this paper to digital form, noticeable signal the receiver to calculate the sensitivity of the method for the calculation was performed. The general strength of the transmission of the modulated signal and digital signal transmission was required for the comparison of optical power. As shown in Figure 3, the general strength of the digital signal transmission system for transmitting a modulated signal compared with the case is improved by at least 10dB.

The Spectral Gain Characteristics of Optical Fiber Weak Light Pre-Amplifier Based on Raman Effect

The spectral information of weak light will be lost in the process of amplification based on photoelectric conversion. To solve this problem, multi-wavelength optical fiber Raman amplifier is used to pre-amplify the weak light before an ordinary color photoelectric sensor. The Raman gains and their effect factors were modeled and analyzed. The results show high intensity gains can be obtained for red, green and blue components of the weak light simultaneously .

Influence of optical amplifier on inter‐satellite microwave photonics links employing a low‐biased Mach‐Zehnder modulator

An exact analytical expression of signal-to-noise ratio (SNR) for inter-satellite microwave photonics links using a low-biased Mach-Zehnder modulator, and with both an optical booster amplifier and a preamplifier, is derived with the method of Bessel expansion and Graf's addition theorem. It is observed that the most limitative noise is changed from the thermal noise to the signal-amplifier spontaneous emission beating noise that arises from the optical preamplifier, and the signal power is seen to increase more compared with the power of noise because of optical preamplifier. Thus, the SNR of system configurations with both an optical booster amplifier and an optical preamplifier can be improved compared with the SNR of system configurations with only an optical booster amplifier. For the preamplifier gain of 20 dB and noise figure of 3 dB, an increase of about 19.7 dB in optimum SNR is accessible. In addition, the effect of optical booster amplifier and preamplifier parameters on the optimum DC bias phase shift and SNR is also investigated.

Error performance analysis for FSO systems with diversity reception and optical preamplification over gamma–gamma atmospheric turbulence channels

The error performance was investigated of free-space optical (FSO) systems that use optical preamplifiers and diversity reception in turbulent atmosphere with gamma–gamma distribution. More specifically, assuming that the dominant sources of the receiver noises are the background light and amplifier spontaneous emission noises, we develop an exact bit-error-rate (BER) expression for binary pulse position modulation (BPPM) by a moment-generating function (MGF) derivative-based method. To gain more insight, we also derive a closed-form asymptotic BER expression for BPPM at high received optical power, by which we obtain the diversity and coding gains of the considered systems. Our analytical results lead to the observations that the attained diversity gain only changes with the gamma-gamma distribution parameters and the number of spatial modes collected by the receiver, while independent on the number of temporal modes passed by the optical preamplifiers. We verify the analytical results by Monte Carlo simulations.

Design and Technical Feasibility of Next 400 GbE 40-km PMD Based on 16<formula formulatype="inline"><tex Notation="TeX">$\,\times\,$</tex> </formula>25 Gbps Architecture

The technical feasibility of a straightforward and cost-effective extension of the current 100 Gb/s Ethernet 40-km physical medium dependent (PMD) architecture for single-mode fiber to a higher speed of 400 Gb/s is demonstrated by means of simulations. A 16-wavelength configuration, each running at 25 Gb/s in non-return-to-zero modulation format and using plain direct detection is numerically analyzed and optimized. It is shown that error-free performance is achievable when a channel plan slightly shifted from the zero-dispersion wavelength of the transmission fiber and having a channel spacing of 400 GHz is utilized. However, to meet the power budget requirement in a fiber having an attenuation coefficient of 0.50 dB/km, a semiconductor optical pre-amplifier with a small-signal gain of 23 dB and transmitters having a minimum average output power of +2.9 dBm and an extinction ratio of 8 dB have to be employed. Based on the calculated design margins, the use of flexible active devices is suggested for span lengths shorter than 40 km.

Colorless and Preamplifierless Reception Using an Integrated Si-Photonic Coherent Receiver

We experimentally study the sensitivity limits of an integrated Si-photonic dual-polarization balanced coherent receiver co-packaged with transimpedance amplifiers. For 28 Gbaud PDM-QPSK and PDM-16QAM signals, we compare colorless and optical preamplifierless reception to the case where an optical preamplifier and optical filters are used before the receiver. Back-to-back receiver sensitivities are evaluated. After propagation over an SMF-28e+ EDFA amplified link and assuming a 3.8 × 10-3 FEC threshold, colorless/preamplifierless reception using the Si-photonic receiver allows for error-free transmission of 112 Gbps PDM-QPSK over 4800 km at a received power of -23 dBm and of 224 Gbps PDM-16QAM over 640 km at a received power of -17 dBm. Finally, a 16 × 112 Gbps PDM-QPSK WDM experiment is carried out. Using the Si-photonic receiver for colorless/preamplifierless reception of all channels, we achieve error-free transmission for all channels over 4160 km at a received power of -21 dBm per channel. Results reveal that the receiver provides excellent sensitivity while allowing us to save cost, footprint, and power if used in a colorless/preamplifierless scheme.

Impact of pointing errors on performance of an intersatellite microwave photonics link with an optical preamplifier under dual-tone modulation

The intersatellite microwave photonics link with an optical preamplifier is affected by third-order intermodulation distortion under dual-tone modulation and pointing errors due to beam wander, which would greatly degrade the link performance. An exact analytical expression for signal-to-noise and distortion ratio (SNDR) is derived considering the signal fade caused by the pointing errors of transceiver. It is shown that, given the desired SNDR and the rms random pointing jitter, an optimum modulation index of Mach-Zehnder modulator exists that minimizes laser output power. Moreover, an optimized model for laser output power and modulation index is established. The effects of the optical preamplifier gain and noise figure on the optimum link performance are also examined. Numerical results show that the minimum laser output power required to achieve the desired SNDR is more sensitive to the preamplifier noise figure. For an SNDR of 20 dB, doubling the preamplifier noise figure results in an 8.95 dB increase in minimum laser output power at the rms pointing jitter of 0.5 μrad.

带前置光放大的星间微波光子链路建模及性能优化

An optical preamplifier is applied to increase the signal-to-noise ratio (SNR) of inter-satellite microwave photonics links considering the large signal loss in distant propagation. An optically preamplified intersatellite microwave photonics links model is established and an analytical expression of SNR is derived with the method of expanding Bessel series and Graf addition theorem. The dominant noise components influence the link performance is confirmed, given the desired SNR, the direct current (DC) bias phase shift of modulator can be optimized so as to minimize the output power of laser diode (LD) under different gain of optical preamplifier, and the effects of the optical preamplifier gain on the minimum output power of LD and optimal DC bias phase shift is also examined. According to the numerical results, the output power of LD needed to achieve the required SNR decreases while increasing the gain of preamplifier, and the corresponding optimal DC bias phase shift decreases first and then increases. For QPSK modulation signal, the output power of LD needed to achieve the SNR of 15.56 dB (BER=10-9) is at least 45 dBm without an optical preamplifier, while the output power of LD is required only 22.57 dBm as the gain of preamplifier is 15 dB.

Development of Automotive LIDAR

SUMMARY We are developing light detection and ranging (LIDAR) sensing technology based on both CMOS single-photon avalanche diodes (SPADs) and scanning systems and on an optical fiber preamplifier. CMOS SPADs are highly sensitive detectors that can detect single photons and can form dense pixel arrays. LIDAR based on an optical preamplifier has a thumb-sized small sensor head.

Effect of Modulation Formats in Hybrid Amplified Radio over Fiber Systems

In this paper, different RoF (radio-over-fiber) based on various laser modulation techniques are analysed and optical preamplifiers results are compared. Then frequency bands for both the cases in hybrid amplification conditions are reported at the end.

Optimization of an analog intersatellite microwave photonics link with an optical preamplifier

An exact analytical expression of the signal-to-noise ratio (SNR) for an intersatellite microwave photonics link with an optical preamplifier is derived considering the signal fade caused by the pointing errors of the transceiver, and an optimized model for laser output power and direct current (DC) bias phase shift of the Mach-Zehnder modulator is established. It is shown that, given the desired SNR and the root mean square (rms) random pointing jitter, an optimal DC bias phase shift exists that minimizes laser output power. The effects of the optical preamplifier parameters on the minimum laser output power and optimal DC bias phase shift are also examined. Numerical results show that the preamplifier noise figure determines the minimum laser output power needed to achieve the desired SNR but affects the optimal DC bias phase shift little. For a SNR of 20dB, doubling the preamplifier noise figure results in a 6.36dB increase in minimum laser output power for rms pointing jitter of 0.4μrad.

Optimization of intersatellite microwave photonic links by utilizing an optical preamplifier under dual-tone modulation

An optical preamplifier is utilized to improve the signal-to-noise and distortion ratio (SNDR) of intersatellite microwave photonic links employing a Mach-Zehnder modulator under dual-tone modulation. The resulting SNDR at an appropriate direct current (DC) bias phase shift is additionally investigated without small-signal approximation in order to optimize the performance of all the links. It is observed that the most limiting factor degrading the SNDR performance is changed, and the fundamental power is seen to increase more compared with the power of third-order intermodulation (IM3) plus noise due to the optical preamplifier. Thus, SNDR can be improved with respect to the case of a nonoptical preamplifier. For the preamplifier gain of 20 dB and noise figure of 3 dB, an increase of about 24 dB in optimum SNDR is accessible. In addition, the optimum DC bias phase shift is found to be insensitive to the preamplifier gain and noise figure, while the optimum SNDR is sensitive to the preamplifier gain and noise figure.

Improving the performance of the four-state continuous-variable quantum key distribution by using optical amplifiers

We propose a method to improve the secret key rates of four-state continuous-variable quantum key distribution by using an optical preamplifier. The modified protocol allows the distribution of higher secret key rates over long distances. Included in this paper is a detailed investigation of the effects of inserting an optical parametric amplifier into the output of the quantum channel in the four-state protocol, which will be instructive and meaningful about the usage of amplifiers in order to achieve the optimal performance of the protocol in a specific scenario.

Optimization of a DPP-BOTDA sensor with 25 cm spatial resolution over 60 km standard single-mode fiber using Simplex codes and optical pre-amplification

Sub-meter distributed optical fiber sensing based on Brillouin optical time-domain analysis with differential pulse-width pairs (DPP-BOTDA) is combined with the use of optical pre-amplification and pulse coding. In order to provide significant measurement SNR enhancement and to avoid distortions in the Brillouin gain spectrum due to acoustic-wave pre-excitation, the pulse width and duty cycle of Simplex coding based on return-to-zero pulses are optimized through simulations. In addition, the use of linear optical pre-amplification increases the receiver sensitivity and the overall dynamic range of DPP-BOTDA measurements. Experimental results demonstrate for first time a spatial resolution of ~25 cm over a 60 km standard single-mode fiber (equivalent to ~240 k discrete sensing points) with temperature resolution of 1.2°C and strain resolution of 24 με.

Demonstration of Record Sensitivities in Optically Preamplified Receivers by Combining PDM-QPSK and M-Ary Pulse-Position Modulation

We present the principle, implementation, and performance of a recently introduced high-sensitivity modulation format based on the combined use of polarization-division-multiplexed quadrature phase-shift keying (PDM-QPSK, or PQ) and m-ary pulse-position modulation (m-PPM). This novel modulation format, termed PQ-mPPM, offers high receiver sensitivity in optically preamplified receivers. We study the sensitivity of the PQ-mPPM format both analytically and experimentally, and compare it to common modulation formats such as PDM-QPSK, m-PPM, differential phase-shift keying, and polarization-switched QPSK. The bandwidth expansion factor of this format is also discussed. A record sensitivity of 3.5 photons per bit at BER = 10-3 is experimentally demonstrated at 2.5 Gb/s with a novel pilot-assisted digital coherent-detection scheme, outperforming PDM-QPSK by about 3 dB.

Improved bit error rate evaluation for optically pre-amplified free-space optical communication systems in turbulent atmosphere

The use of an optical pre-amplifier at the receiver of free-space optical (FSO) communication systems necessitates the consideration of both turbulence and amplified spontaneous emission (ASE) noise in performance modelling. Until now, this problem has been typically approached by the use of a Gaussian approximation (GA) for the conditional probability of error with averaging then performed using the received irradiance probability density function (PDF) (governed by scintillation). However, the GA is deficient as it only uses the first two moments. Moment generating function (MGF) techniques, notably the Chernoff bound (CB) and modified Chernoff bound (MCB), are used to evaluate the bit error rate performance of an optically pre-amplified FSO system in the presence of both atmospheric turbulence and ASE noise. The MGF-based methods incorporate a fuller statistical description of the signal and noise processes encountered in the optically pre-amplified case when compared to the GA. The lognormal, gamma–gamma, K and negative exponential distributions have been used to characterise the weak, moderate, strong and saturated turbulence regimes. The MCB gives the tightest bound upon the BER compared to the CB, particularly at lower gains, and, as it also can be exceeded by the GA at higher gains, it is a logical method to use in general.

Performance evaluation of optically preamplified digital pulse position modulation turbulent free-space optical communication systems

Optical preamplification introduces non-Gaussian electrical domain noises (beat noises) to digital pulse position modulation (DPPM) free-space optical (FSO) communication systems impaired by atmospheric turbulence, which do not appear for a simple PIN photodiode-based FSO receivers and thus necessitate a more sophisticated approach to bit error rate (BER) modelling. To explore this BER performance analyses, notably the Gaussian approximation, Chernoff bound and modified Chernoff bound (MCB), for such a system are presented and the MCB is seen to be an appropriate technique to use. Furthermore, the effectiveness of spatial diversity techniques, specifically aperture averaging, in mitigating the turbulence effect is investigated. The gamma-gamma distribution model is used to characterise the whole range of turbulence conditions. The results reveal the superiority of DPPM with improved receiver sensitivity (at a binary data rate 2.5-Gb/s and at typical FSO BER of 10 -9 ) of about 7-9-dB [for coding level of 5 and optical link length (for turbulent interaction) of 1500-m] more than an equivalent optically preamplified on-off keying non-return-to-zero approach, depending on the level of turbulence.