共查询到20条相似文献,搜索用时 10 毫秒
1.
The effects of chromatic dispersion (CD), polarization-mode dispersion (PMD), and polarization-dependent loss (PDL) on the intensity noise suppression of spectrum-sliced incoherent light sources achieved by using gain-saturated (GS) semiconductor optical amplifiers (SOAs) are investigated. Passing the spectrum-sliced incoherent light through SOAs, the excess intensity noise (EIN) originating from beating of spontaneous emission against itself can be greatly reduced. However, since the noise suppression is achieved by an elaborate balancing between numerous frequency/polarization components of light, thus, forming a high correlation between them, it is vulnerable to frequency/polarization-dependent optical phenomena. Through Q-factor and bit error rate (BER) measurements, this paper shows that CD, PMD, or PDL deteriorates the SOA-based noise suppression technique by breaking the correlation. Spectral analysis is also performed to investigate the frequency dependency of these effects. It is shown that CD and PMD negate the noise suppression giving rise to intensity noise from high frequencies, whereas there is no frequency dependence for PDL effects. Therefore, CD-, PMD-, or PDL-induced penalties for incoherent light sources using the SOA-based noise suppression technique are considerably greater than those produced by pulse broadening or distortion alone. 相似文献
2.
《Optical Fiber Technology》2007,13(1):72-77
This paper reduces the impact of backreflection in WDM single-fiber loopback access networks by using a gain-saturated semiconductor optical amplifier (SOA). The backreflection lights from two sources are taken into consideration, the continuous wave (CW) light at the central office (CO) (Reflection-I) and the modulated signal at the optical network unit (ONU) (Reflection-II). A SOA is placed at the ONU to reduce the intensity noise caused by Reflection-II. To investigate the effect by the proposed technique, an experiment creating multiple reflection points is conducted. The results show that a loss budget of 10 dB without SOA can be increased to 16 dB. 相似文献
3.
We investigate the FWM efficiency of incoherent light in a dispersion-shifted fiber (DSF) using a spectrum-sliced fiber amplifier light source. A theoretical model is provided to describe the FWM mechanism of incoherent light. The FWM efficiencies of coherent and incoherent light are compared theoretically and experimentally. Unlike the FWM of coherent light, the FWM signals of incoherent light are mostly generated by nondegenerate FWM regardless of the number of input signals. Thus, when two input signals are mixed, incoherent light has about 6 dB higher mixing efficiency than coherent light due to the difference in their degeneracy factor 相似文献
4.
Jae-Seung Lee 《Lightwave Technology, Journal of》1996,14(10):2197-2201
We have derived the beat-noise-limited signal-to-noise ratio (SNR) of spectrum-sliced incoherent light sources, including optical modulation effects. SNR changes significantly in time depending on the received optical pulse shape and the receiver electrical filter. Thus, the optimum decision point at the optical receiver may be much different from the peak signal point and the sampled SNR may be different from the continuous-wave SNR. To obtain high SNR, small rise and fall times are required and the non-return-to-zero modulation format is recommended 相似文献
5.
6.
Wavelength channel data rewrite using saturated SOA modulator for WDM networks with centralized light sources 总被引:1,自引:0,他引:1
This paper describes a method for realizing the efficient utilization of wavelength resources in wavelength-division multiplexing networks with centralized light sources. Using a deeply saturated semiconductor optical amplifier (SOA) modulator located in a remote node (RN), we erase the data on a downstream signal with a low extinction ratio and modulate it with new data to generate an upstream signal. Thus, we use only one wavelength for bidirectional transmission between a center node and an RN, without placing lasers at the RN. In this paper, we analyze the data suppression characteristic of the SOA using a large signal model. We also estimate the bit error rate degradation in the presence of an unsuppressed downstream bit pattern in an upstream signal. We then report experimental results that confirm the basic characteristics of the wavelength channel data rewriter, which we constructed using a linear amplifier and an SOA. Finally, we provide the results of a data transmission experiment that we undertook using the data rewriter. 相似文献
7.
Hoon Kim Ho Chul Ji Chul Han Kim 《Photonics Technology Letters, IEEE》2006,18(14):1542-1544
We investigate the effects of intraband crosstalk on the intensity noise suppression of spectrum-sliced incoherent light sources using semiconductor optical amplifiers (SOAs). Both Q-factor and electrical spectrum measurements clearly show that intraband crosstalk deteriorates the SOA-based noise suppression by breaking the correlation between optical frequency components of light. 相似文献
8.
9.
We investigate wideband reduction of excess intensity noise in incoherent light for application to spectrum-sliced WDM systems. The noise reduction scheme is based on optoelectronic feedforward compensation. We derive expressions for the probability density function of noise-reduced incoherent light and present measurements that are in good agreement with theory. We evaluate the significant levels of improvement obtainable in the capacity of spectrum-sliced WDM channels. For example, to obtain a signal-to-noise ratio of 50, a noise-reduced channel requires six times less optical bandwidth than a spectral slice without noise reduction 相似文献
10.
Keang-Po Ho Shien-Kuei Liaw Clinlon Lin 《Electronics letters》1996,32(24):2210-2211
Semiconductor laser amplifiers cause both distortion and crosstalk in WDM systems due to gain saturation. A method using light injection is experimentally demonstrated to reduce distortion and crosstalk. In a two-channel experiment with a data rate of 2.5 Gbit/s, it is found that light injection can eliminate the BER floor due to distortion and crosstalk 相似文献
11.
Noise suppression effect in wavelength conversion using an externally light injected laser diode is described. Signal fluctuation for the “on” level resulting from signal-spontaneous beat noise from optical amplifiers can be suppressed by utilizing the threshold characteristic in the conversion process 相似文献
12.
Reflective semiconductor optical amplifier (RSOA) based wavelength division multiplexed radio-over-fiber passive optical network (WDM−RoF−PON) has been proposed and demonstrated, to transmit 2.5 Gbps baseband (BB) and 1.25 Gbps wireless data in downstream and 1 Gbps BB data signal in upstream over 25-km single-mode fiber (SMF), and wireless downstream signal over 25-km SMF as well as 5.2 m free space in air. In the downstream, 2.5 Gbps BB data and 1.25 Gbps wireless data are modulated using single-electrode Mach–Zehnder modulator (SD-MZM) based on double-sideband with optical carrier suppression (DSBCS) scheme and simultaneously transmitted by incoherent light injection technique and employing fiber Bragg grating (FBG) at the base station. RSOA is utilized at the user end to reuse the carrier for uplink transmission. High receiver sensitivity, low bit-error-rate (BER) and excellent eye-diagram, eye height are achieved in our proposed network system and the results affirm the acceptability of proposed RSOA based WDM−RoF−PON. 相似文献
13.
We propose and experimentally demonstrate a wavelength division multiplexed (WDM) ring network employing a centralized multiwavelength light source to supply all nodes with optical carriers of precise wavelength spacing. This approach overcomes the problem of monitoring and controlling the wavelengths of optical sources dispersed throughout the network. A four-node test bed using optical lattice-type add-drop multiplexing filters and a multiwavelength light source based on resonant cavity-enhanced four wave mixing in a Fabry-Perot laser diode was constructed to demonstrate the feasibility of the proposed method. The effects of coherent crosstalk in such networks are analyzed, and methods such as phase scrambling or the use of a pulsed optical source are shown to significantly reduce the effects of coherent crosstalk. The use of four-port add-drop multiplexer (ADM) filters instead of 1:n optical wavelength multiplexer/demultiplexers to implement the wavelength add-drop function at each node is shown to lead to a broader transmission bandwidth for each channel and also easier compatibility with the coherent crosstalk suppression mechanisms described 相似文献
14.
H. Hatakeyama K. Naniwae K. Kudo N. Suzuki S. Sudo S. Ae Y. Muroya K. Yashiki K. Satoh T. Morimoto K. Mori T. Sasaki 《Photonics Technology Letters, IEEE》2003,15(7):903-905
We report on the first demonstrated near-complete coverage of the S-, C-, and L-bands using six different ranges of wavelength-selectable microarray light sources (WSLs) based on a distributed-feedback (DFB) laser diode (LD) array. The six devices were fabricated on only two wafers. Each device has a tuning range of more than 15 nm, a sidemode suppression ratio of over 40 dB, and a fiber-coupled power greater than around 10 mW. 相似文献
15.
Zhihong Li Guifang Li 《Photonics Technology Letters, IEEE》2006,18(7):811-813
Saturated semiconductor optical amplifiers (SOAs) can be used as booster amplifiers for dense wavelength-division-multiplexing (DWDM) return-to-zero differential phase-shift keying (RZ-DPSK) transmitters. By introducing time interleaving (TI), both linear crosstalk induced by WDM components and nonlinear crosstalk induced by SOA nonlinearities are suppressed. Receiver sensitivities for four-channel DWDM RZ-DPSK signals with 100- and 50-GHz channel spacing were improved 2.2 and 4.2 dB, respectively, by applying proper TI between adjacent channels. A 1-dB gain enhancement was also achieved. 相似文献
16.
G. B. Volobuev N. N. Semenov V. D. Lukyanchikov V. I. Ledovskikh 《Radioelectronics and Communications Systems》2008,51(4):196-201
It is considered intrusion protection communication systems, which provide elimination of mutual signals of signaling devices suppression, using random number generators, providing almost tenfold increase noise immunity of telecommunication systems and the algorithm, providing improve its response speed. 相似文献
17.
The paper analyses the effects of intra-channel four-wave mixing (IFWM) on the high-speed optical fiber communication system. A new code format is developed with double 0 and double π phase separating 1 code; it can decrease the transmission penalty from fiber nonlinearity by counteracting the perturbation terms of IFWM. From the simulation of transmission of two classic code data "11011" and "11100", we find that our proposed code format has a better suppression effect than the alternative modulation inversion (AMI) or the normal RZ format and supports a wider pulse mode. In a 40 Gbps system, the AMI format is 2 dB less than the RZ format, and our proposed format is 1 dB less than the AMI format when a 1 dB eye open penalty is taken as a metewand. Moreover,it can be realized as easily as the AMI format. 相似文献
18.
The impact of cross-phase modulation (XPM) is measured on positive and negative dispersion fibre. The exponential build-up of XPM over positive dispersion fibre indicates amplification due to modulation instability. Methods for suppressing XPM crosstalk are also demonstrated 相似文献
19.
Neokosmidis I. Kamalakis T. Chipouras A. Sphicopoulos T. 《Lightwave Technology, Journal of》2005,23(3):1137-1144
The performance of a wavelength-division multiplexing (WDM) optical network can be severely degraded due to fiber nonlinear effects. In the case where nonzero dispersion (NZD) fibers are employed, the four-wave mixing (FWM) effect sets an upper limit on the input power, especially in the case of narrow channel spacing. In order to reduce FWM-induced distortion two new techniques, the hybrid amplitude-/frequency-shift keying (ASK/FSK) modulation and the use of prechirped pulses are investigated. It is shown that both techniques can greatly improve the Q-factor in a 10 Gb/s WDM system. This happens even for very high input powers (/spl sim/10 dBm), where the degradation of the conventional WDM system is prohibitively high. The proposed methods are also applied and tested in higher bit rates (40 Gb/s). It is deduced that although the hybrid ASK/FSK modulation technique marginally improves the system performance, the optical prechirp technique can still be used to greatly increase the maximum allowable input power of the system. 相似文献
20.
The applications of Raman amplifiers as repeater amplifiers or post-transmitter amplifiers in a high-density WDM system are theoretically investigated. There exists an optimum pump power which results in maximum amplifier gain. The result shows that amplifier gains up to 50 dB and 20 dB are achievable for use as a repeater and a post-transmitter amplifier, respectively.<> 相似文献