Experimental linewidth-insensitive coherent analog optical link

Sabido, D.J.M.; Tabara, M.; Fong, T.K.; Kalman, Robert F.; Kazovsky, L.G.

doi:10.1109/50.336063

Cited by 10 publications

(7 citation statements)

References 28 publications

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“…1(a) and (b), the maximum RF power is usually limited by the nonlinearity of the EOM [6]. SFDR is experimentally measured using the setup given in [2].…”

Section: Dynamic Range Analysismentioning

confidence: 99%

“…, employing a single OA is given by (see Table II for symbol definitions) (2) where is the total power spectral density (PSD) of the additive noise at the output of the photodetector.…”

Section: A Dynamic Range Of the Direct Detection Linkmentioning

confidence: 99%

“…1(a) and (b), respectively, including the component specifications and parameters, and the WIRNA receiver is given in [2].…”

Section: A Direct and Coherent Detection Systemsmentioning

confidence: 99%

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Dynamic range of optically amplified RF optical links

Sabido

Kazovsky

2001

IEEE Trans. Microwave Theory Techn.

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We investigated, theoretically and experimentally, the effect of optical amplification on the dynamic range performance of both externally modulated direct detection and coherent RF optical links. Our results show that, for low-to medium-loss links, a direct detection link with or without an optical amplifier, depending on the loss range, gives the best dynamic range. For high-loss links, the best link to use is a coherent link with the optical amplifier after the modulator. We also showed that the position of an amplifier is an important design parameter; it determines whether or not an optical amplifier improves the link's dynamic range.Index Terms-Analog systems, erbium, microwave technology, optical amplifier, optical communication, optical fiber amplifier, optical fiber communication, optical signal processing.

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“…1(a) and (b), the maximum RF power is usually limited by the nonlinearity of the EOM [6]. SFDR is experimentally measured using the setup given in [2].…”

Section: Dynamic Range Analysismentioning

confidence: 99%

“…, employing a single OA is given by (see Table II for symbol definitions) (2) where is the total power spectral density (PSD) of the additive noise at the output of the photodetector.…”

Section: A Dynamic Range Of the Direct Detection Linkmentioning

confidence: 99%

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Dynamic range of optically amplified RF optical links

Sabido

Kazovsky

2001

IEEE Trans. Microwave Theory Techn.

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“…Assuming this is the case and neglecting dc terms, the photocurrent can be expressed as: (5) where is the IF frequency, , and the values of the amplitude, , and the additive noise current, , depend on whether a single or balanced detector configuration is used. We define the amplitude for a balanced receiver as (6) where is the detector responsivity. The single detector amplitude, , is half since the single photodetector allows only half of the optical power to be used.…”

Section: System Descriptionmentioning

confidence: 99%

“…Conventionally, these systems have employed direct detection schemes; however recent links utilizing coherent detection have demonstrated large dynamic range and low noise figures [5], [6]. In addition, coherent detection facilitates high channel packing densities for wavelength division multiplexed (WDM) systems, has increased sensitivity over direct detection schemes, and allows for angle modulation formats.…”

Section: Introductionmentioning

confidence: 99%

Phase noise in coherent analog AM-WIRNA optical links

Taylor

Poor

Forrest

1997

J. Lightwave Technol.

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Coherent analog amplitude modulated-wideband rectifier narrowband (AM-WIRNA) systems have been the focus of many recent studies because of their high performance and relative immunity to phase noise compared to angle modulated systems. Despite their natural advantages over angle modulated systems, AM-WIRNA receivers are still vulnerable to phase noise because of distortion of their phase broadened signals in a finite bandwidth system. We present the first numerical analysis of the effects of this distortion on the performance of AM-WIRNA systems. The analysis accurately models the power spectral density of the phase-to-intensity noise with a root-mean-square deviation from the averaged experimental noise spectrum of 1.2 dB and a maximum deviation of 3.8 dB in the modulation range of <2 GHz. The accuracy of the analysis is limited primarily by nonidealities in the AM-WIRNA receiver and the accuracy of the analytical intermediate frequency (IF) filter model. Optimal link designs are presented which minimize the impact of phase-to-distortion noise in AM-WIRNA systems. We present experimental data from AM-WIRNA links which use both external cavity and distributed feedback lasers for the signal and local oscillator sources. The numerical analysis predicts the link signal-to-noise ratio (SNR) for different signal laser powers to within 1.4 dB of experiment. We find that systems requiring high SNR such as phased array antennas and AM-CATV are significantly affected by this noise.

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Impact of laser phase noise on binary- andM-ary-PSK coherent optical systems using multiple optical amplifiers

Farokhrooz

Tafti

Raina

1996

Microw. Opt. Technol. Lett.

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%? 100.0 m. 1 so.o=/ v -120.22 START 0.045000WO CHI SrOP 0 . -GHx Figure 3 Relative phase shift between the inverter and the noninverter structuresThe use of a dual-gate transistor as part of the auxiliary amplifier of the second loop, allowing electric control of the intermodulation and avoiding the need of a cut-andtry adjustment in attenuation. Dual-gate FETs have the advantage of gain varying, without phase changes The inclusion of a lumped phase inverter (bifilar, ferrite based) and a corresponding dummy one, noninverter, just to ensure the symmetry of the insertion losses and the correct phase relation between the two loop branches. Figure 3 shows the actual phase response of these devices in the range of 0.045-2.6 GHzThe use of two capacitors (C, and C,, in Figure 2) in series with the transmission lines, in the second loop, can provide a better electric compensation of the auxiliary amplifier of this loop, resulting in an impressive performance improvement, especially at low frequen-DB[S2l] AMP 30.00 0.0000 -30.00 0.1000 0.8OOO PREP-CHZ I .so0 Figure 4The relative intermodulation improvement. The upper curve is the measured output of the system without feed forward; the difference between that curve and the lower ones is the intermodulation reduction. (a) C , nonexistent, C , = 1 nF; (b) C, = 1 nF, C , = 47 p F (c) C, = 220 pF, C , = 47 pF cies, when compared with previous results [l]. If the capacitors are replaced by varactors, electrical control of the intermodulation reduction shape can be achieved. Figure 4 shows the responses of an implemented prototype under several conditions of the compensating capacitors. As shown, it is possible to achieve an intermodulation-level reduction greater than 25 dB over more than 3 octaves. This improvement allows driving the amplifier 8 dB higher, for the same desired linearity (reducing the required backoff). CONCLUSIONSSome changes on the usual implementation of feed-forward power amplifiers have been presented, aiming at broadband operation. The simulated and measured performances have shown approximately 25-dB improvement in intermodulation canceling over more than 800-MHz bandwidth. This broadband response could be improved even further if the circuit were implemented in a monolithic form and if more advanced phase-inversion structures were used. ABSTRACTThis study evaluates the pe$ormance of binary-and M-ary-PSK coherent optical systems using cascaded optical amplifiers in the presence of noise originating from the detector, receiver, optical amplijiers, and the laser phase fluctuations. Our results on the analysis of these systems indicate that at an amplifier input power of -20 dBm and a system length of 10,000 km, the power penalties incurred due to the laser phase noise at a bit error rate of 10linewidths of 770. 31, 101.86, and 6.37 kHz for binary-PSK four-PSK, and eight-PSK systems, respectively. 0 1996 John Wiley & Sons, Inc. correspond to 0.57, 0.99, and 3.38 dB at " = LSYNCHRO-. -L

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Experimental linewidth-insensitive coherent analog optical link

Cited by 10 publications

References 28 publications

Dynamic range of optically amplified RF optical links

Dynamic range of optically amplified RF optical links

Phase noise in coherent analog AM-WIRNA optical links

Impact of laser phase noise on binary- andM-ary-PSK coherent optical systems using multiple optical amplifiers

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