The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
F. Koyama - One of the best experts on this subject based on the ideXlab platform.
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Optical Preamplifier using Optical modulation of amplified spontaneous emission in saturated semiconductor Optical amplifier
Journal of Lightwave Technology, 2004Co-Authors: Takeshi Yamatoya, F. KoyamaAbstract:This paper demonstrates a novel Optical Preamplifier using Optical modulation of amplified spontaneous emission (ASE) emitted from a saturated semiconductor Optical amplifier (SOA). Requirements on Optical alignments and antireflection coating for SOAs can be relaxed and the elimination of an Optical filter gives us a large tolerance of an input light wavelength in the proposed Optical Preamplifier. A small-signal gain of a fabricated Preamplifier was over 13.5 dB for an input power of below -20 dBm. An Optical gain bandwidth was over 60 nm. We measured the small-signal response of the Optically modulated ASE. The 3 dB bandwidths at SOA bias currents of 200, 300, and 400 mA were 5.8, 12.6, and 16.5 GHz, respectively. We also investigated improvements in receiver sensitivities with the proposed Optical Preamplifier. Our calculation shows a possibility of 10 dB improvement in receiver sensitivities by using the Optical Preamplifier at 10 Gb/s. The measured receiver sensitivity was -22.7 dBm at 10 Gb/s with the Optical Preamplifier, which is corresponding to an improvement of 2.5 dB in the receiver sensitivity. Further improvements of the receiver sensitivity can be expected by optimizing the structure of SOAs for saturating ASE.
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Optical Preamplifier using antireflection-coating-free semiconductor Optical amplifier with signal-inverted ASE
IEEE Photonics Technology Letters, 2003Co-Authors: Takeshi Yamatoya, F. KoyamaAbstract:We fabricated an antireflection (AR)-coating-free semiconductor Optical amplifier (SOA) with an absorbing region for an Optical Preamplifier. In the fabricated SOA, the resonance of light was fully suppressed so that the amplitude of the ripple of amplified spontaneous emission (ASE) spectra was as small as 0.36 dB, which is comparable to conventional SOAs with AR coating at both facets. We formed an Optical Preamplifier using the AR-coating-free SOA. The gain saturation of the SOA gives us the signal conversion to ASE and the amplification of the signal. The small-signal fiber-to-fiber and chip gain of the Preamplifier were 11.4 and 20.0 dB, respectively. The 3-dB Optical gain bandwidth of the Preamplifier was about 30 nm.
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High-Speed Operation of Optical Preamplifier Using Inverted Amplified Spontaneous Emission Signal of Saturated Semiconductor Optical Amplifier
Japanese Journal of Applied Physics, 2002Co-Authors: Takeshi Yamatoya, F. KoyamaAbstract:We investigate the dynamics of an Optical Preamplifier using an inverted amplified spontaneous emission (ASE) signal of a saturated semiconductor Optical amplifier (SOA). The small-signal response of the converted ASE was measured and its 3 dB bandwidth was over 9 GHz when the injection current of the SOA was increased to more than 200 mA. The rise and fall times of the converted output ASE were also evaluated. In addition, we achieved 10 Gbit/s operation of the proposed Preamplifier. The minimum receiver sensitivity was improved by 7 dB using the Preamplifier for the 10 Gbit/s signal.
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10 Gb/s operation of Optical Preamplifier using inverted ASE signal of saturated semiconductor Optical amplifier
Summaries of Papers Presented at the Lasers and Electro-Optics. CLEO '02. Technical Diges, 2002Co-Authors: Takeshi Yamatoya, F. KoyamaAbstract:Summary form only given. Semiconductor Optical amplifiers (SOAs) are attractive for use in metro Optical networks as well as in access networks. We proposed an Optical Preamplifier using the Optical modulation of ASE in a saturated SOA. The proposed Preamplifier only needs a single connection between a fiber and the SOA, which relaxes requirements on AR coating and assembling with a single mode fiber. In addition, this Preamplifier can potentially avoid using a narrow-band Optical filter. In this paper, we investigate the high-speed response of the Preamplifier and demonstrate 10 Gb/s operation. In our proposed Preamplifier, an input signal is converted to the modulation of the ASE due to the saturation characteristic in an SOA, resulting in the amplification of the signal. We investigated the high-speed response of the Optical Preamplifier. We used a polarization insensitive GaInAsP bulk SOA. We also investigated the improvement in receiver sensitivity of the Optical Preamplifier. We measured bit error rate (BER) curves with and without the Optical Preamplifier. The minimum receiver sensitivity was improved by about 10, 8 and 7 dB for 2.5, 5 and 10 Gb/s signal, respectively.
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Novel Optical Preamplifier with inverted ASE signal of semiconductor Optical amplifier
Proceedings 27th European Conference on Optical Communication (Cat. No.01TH8551), 2001Co-Authors: Takeshi Yamatoya, F. Koyama, Kenichi IgaAbstract:We propose and demonstrate a novel Optical Preamplifier using an inverted signal of amplified spontaneous emission (ASE) of a semiconductor Optical amplifier (SOA). The input signal is converted to the modulation of the ASE because of saturation characteristics. The proposed device can not only amplify Optical signal but can also suppress the intensity noise of the input signal under the saturation regime. The receiver sensitivity was improved by 10 dB at 1 Gbit/s using the proposed Preamplifier. Also, the intensity noise of a 1 Gbit/s spectrum-sliced light was significantly suppressed using the nonlinear characteristics of the Preamplifier. A larger gain and a higher speed can be expected simultaneously at a lower input signal power by increasing the length of SOA. The proposed device will be useful in low cost access and metro networks.
Takeshi Yamatoya - One of the best experts on this subject based on the ideXlab platform.
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Optical Preamplifier using Optical modulation of amplified spontaneous emission in saturated semiconductor Optical amplifier
Journal of Lightwave Technology, 2004Co-Authors: Takeshi Yamatoya, F. KoyamaAbstract:This paper demonstrates a novel Optical Preamplifier using Optical modulation of amplified spontaneous emission (ASE) emitted from a saturated semiconductor Optical amplifier (SOA). Requirements on Optical alignments and antireflection coating for SOAs can be relaxed and the elimination of an Optical filter gives us a large tolerance of an input light wavelength in the proposed Optical Preamplifier. A small-signal gain of a fabricated Preamplifier was over 13.5 dB for an input power of below -20 dBm. An Optical gain bandwidth was over 60 nm. We measured the small-signal response of the Optically modulated ASE. The 3 dB bandwidths at SOA bias currents of 200, 300, and 400 mA were 5.8, 12.6, and 16.5 GHz, respectively. We also investigated improvements in receiver sensitivities with the proposed Optical Preamplifier. Our calculation shows a possibility of 10 dB improvement in receiver sensitivities by using the Optical Preamplifier at 10 Gb/s. The measured receiver sensitivity was -22.7 dBm at 10 Gb/s with the Optical Preamplifier, which is corresponding to an improvement of 2.5 dB in the receiver sensitivity. Further improvements of the receiver sensitivity can be expected by optimizing the structure of SOAs for saturating ASE.
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Optical Preamplifier using antireflection-coating-free semiconductor Optical amplifier with signal-inverted ASE
IEEE Photonics Technology Letters, 2003Co-Authors: Takeshi Yamatoya, F. KoyamaAbstract:We fabricated an antireflection (AR)-coating-free semiconductor Optical amplifier (SOA) with an absorbing region for an Optical Preamplifier. In the fabricated SOA, the resonance of light was fully suppressed so that the amplitude of the ripple of amplified spontaneous emission (ASE) spectra was as small as 0.36 dB, which is comparable to conventional SOAs with AR coating at both facets. We formed an Optical Preamplifier using the AR-coating-free SOA. The gain saturation of the SOA gives us the signal conversion to ASE and the amplification of the signal. The small-signal fiber-to-fiber and chip gain of the Preamplifier were 11.4 and 20.0 dB, respectively. The 3-dB Optical gain bandwidth of the Preamplifier was about 30 nm.
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High-Speed Operation of Optical Preamplifier Using Inverted Amplified Spontaneous Emission Signal of Saturated Semiconductor Optical Amplifier
Japanese Journal of Applied Physics, 2002Co-Authors: Takeshi Yamatoya, F. KoyamaAbstract:We investigate the dynamics of an Optical Preamplifier using an inverted amplified spontaneous emission (ASE) signal of a saturated semiconductor Optical amplifier (SOA). The small-signal response of the converted ASE was measured and its 3 dB bandwidth was over 9 GHz when the injection current of the SOA was increased to more than 200 mA. The rise and fall times of the converted output ASE were also evaluated. In addition, we achieved 10 Gbit/s operation of the proposed Preamplifier. The minimum receiver sensitivity was improved by 7 dB using the Preamplifier for the 10 Gbit/s signal.
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10 Gb/s operation of Optical Preamplifier using inverted ASE signal of saturated semiconductor Optical amplifier
Summaries of Papers Presented at the Lasers and Electro-Optics. CLEO '02. Technical Diges, 2002Co-Authors: Takeshi Yamatoya, F. KoyamaAbstract:Summary form only given. Semiconductor Optical amplifiers (SOAs) are attractive for use in metro Optical networks as well as in access networks. We proposed an Optical Preamplifier using the Optical modulation of ASE in a saturated SOA. The proposed Preamplifier only needs a single connection between a fiber and the SOA, which relaxes requirements on AR coating and assembling with a single mode fiber. In addition, this Preamplifier can potentially avoid using a narrow-band Optical filter. In this paper, we investigate the high-speed response of the Preamplifier and demonstrate 10 Gb/s operation. In our proposed Preamplifier, an input signal is converted to the modulation of the ASE due to the saturation characteristic in an SOA, resulting in the amplification of the signal. We investigated the high-speed response of the Optical Preamplifier. We used a polarization insensitive GaInAsP bulk SOA. We also investigated the improvement in receiver sensitivity of the Optical Preamplifier. We measured bit error rate (BER) curves with and without the Optical Preamplifier. The minimum receiver sensitivity was improved by about 10, 8 and 7 dB for 2.5, 5 and 10 Gb/s signal, respectively.
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Novel Optical Preamplifier with inverted ASE signal of semiconductor Optical amplifier
Proceedings 27th European Conference on Optical Communication (Cat. No.01TH8551), 2001Co-Authors: Takeshi Yamatoya, F. Koyama, Kenichi IgaAbstract:We propose and demonstrate a novel Optical Preamplifier using an inverted signal of amplified spontaneous emission (ASE) of a semiconductor Optical amplifier (SOA). The input signal is converted to the modulation of the ASE because of saturation characteristics. The proposed device can not only amplify Optical signal but can also suppress the intensity noise of the input signal under the saturation regime. The receiver sensitivity was improved by 10 dB at 1 Gbit/s using the proposed Preamplifier. Also, the intensity noise of a 1 Gbit/s spectrum-sliced light was significantly suppressed using the nonlinear characteristics of the Preamplifier. A larger gain and a higher speed can be expected simultaneously at a lower input signal power by increasing the length of SOA. The proposed device will be useful in low cost access and metro networks.
I. Jacobs - One of the best experts on this subject based on the ideXlab platform.
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Optical Preamplifier receiver for spectrum-sliced WDM
Journal of Lightwave Technology, 1997Co-Authors: V. Arya, I. JacobsAbstract:Spectrum-slicing provides a low-cost alternative to the use of multiple coherent lasers for wavelength division multiplexing (WDM) applications by utilizing spectral slices of a single broadband noise source for creating the multichannel system. In this paper we analyze the performance of both p-i-n and Optical Preamplifier receivers for spectrum-sliced WDM using actual noise distributions, and the results are compared with those using the Gaussian approximation. This extends prior results of Marcuse for the detection of deterministic signals in the presence of Optical amplifier and receiver noise. Although the methodology is similar, the results are considerably different when the signal is itself noise-like. For the case of noise-like signals, it is shown that when an Optical Preamplifier receiver is used, there exists an optimum filter bandwidth which minimizes the detection sensitivity for a given error probability. Moreover the evaluated detection sensitivity, in photons/bit, represents an order of magnitude (>10 dB) improvement over conventional detection techniques that employ p-i-n receivers. The Gaussian approximation is shown to be overly conservative when dealing with small ratios of the receiver Optical to electrical bandwidth, for both p-i-n and Preamplifier receivers.
V. Arya - One of the best experts on this subject based on the ideXlab platform.
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Optical Preamplifier receiver for spectrum-sliced WDM
Journal of Lightwave Technology, 1997Co-Authors: V. Arya, I. JacobsAbstract:Spectrum-slicing provides a low-cost alternative to the use of multiple coherent lasers for wavelength division multiplexing (WDM) applications by utilizing spectral slices of a single broadband noise source for creating the multichannel system. In this paper we analyze the performance of both p-i-n and Optical Preamplifier receivers for spectrum-sliced WDM using actual noise distributions, and the results are compared with those using the Gaussian approximation. This extends prior results of Marcuse for the detection of deterministic signals in the presence of Optical amplifier and receiver noise. Although the methodology is similar, the results are considerably different when the signal is itself noise-like. For the case of noise-like signals, it is shown that when an Optical Preamplifier receiver is used, there exists an optimum filter bandwidth which minimizes the detection sensitivity for a given error probability. Moreover the evaluated detection sensitivity, in photons/bit, represents an order of magnitude (>10 dB) improvement over conventional detection techniques that employ p-i-n receivers. The Gaussian approximation is shown to be overly conservative when dealing with small ratios of the receiver Optical to electrical bandwidth, for both p-i-n and Preamplifier receivers.
Guhao Zhao - One of the best experts on this subject based on the ideXlab platform.
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Impact of pointing errors on performance of an intersatellite microwave photonics link with an Optical Preamplifier under dual-tone modulation.
Applied Optics, 2013Co-Authors: Shanghong Zhao, Yongjun Li, Xiang Wang, Guhao ZhaoAbstract: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.
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Modelling and optimization of Optically preamplified inter-satellite microwave photonics links
SCIENTIA SINICA Informationis, 2013Co-Authors: Zihang Zhu, Shanghong Zhao, Xiang Wang, Xingchun Chu, Hui Zhang, Rui Hou, Guhao ZhaoAbstract: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.
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Influence of Optical amplifier on inter-satellite microwave photonics links employing a low-biased Mach-Zehnder modulator
IET Optoelectronics, 2013Co-Authors: Shanghong Zhao, Yongjun Li, Xiang Wang, Wei Jiang, Guhao ZhaoAbstract: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.
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optimization of an analog intersatellite microwave photonics link with an Optical Preamplifier
Journal of The Optical Society of America A-optics Image Science and Vision, 2012Co-Authors: Shanghong Zhao, Yongjun Li, Xiang Wang, Guhao ZhaoAbstract: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 20 dB, doubling the Preamplifier noise figure results in a 6.36 dB increase in minimum laser output power for rms pointing jitter of 0.4 μrad.
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optimization of intersatellite microwave photonic links by utilizing an Optical Preamplifier under dual tone modulation
Applied Optics, 2012Co-Authors: Shanghong Zhao, Yongjun Li, Xiang Wang, Wei Jiang, Guhao ZhaoAbstract: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.