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High Dynamic Range, 100 km Digital Radio-over-Fiber Links
Published in Chi H. Lee, Microwave Photonics, 2017
Vincent J. Urick, Frank Bucholtz, Eric E. Funk
where grf is given by Equation 6.3 and the intrinsic shot noise power spectral density has been reduced by a factor of four to account for the loss in the matching circuit of the photodiode. It is often useful to normalize the output noise power spectral density from a photonic link to the DC power at the output. Termed relative intensity noise (RIN), this quantity is often employed to describe noise originating in the optical domain relative to the average laser power. Here, it is used in a general sense as it facilitates compact equations useful for system design. As discussed after Equation 6.2, the output noise current sourced from the photodiode itself is split between the matching circuit and the load, whereas the total DC photocurrent corresponds to the total average optical power. Therefore, the total RIN will be defined as () RINtotal=4NtotalIdc2Rout
Optical Wireless Receiver Design
Published in Roberto Ramirez-Iniguez, Sevia M. Idrus, Ziran Sun, Optical Wireless Communications, 2008
Roberto Ramirez-Iniguez, Sevia M. Idrus, Ziran Sun
The performance of a receiver degrades as a result of several factors, including laser linewidth, relative intensity noise (RIN) of the source, and receiver noise. These effects have an impact on the maximum transmission distance and signal coverage area. The performance of an optical digital link is measured by the bit error rate (BER). Conversely, in an analog optical link, the performance of the receiver is measured by the SNR or the carrier-to-noise ratio (CNR). An example of such an analog system is the optical wireless CATV system, where multiple analog or digital TV signals (or both) are combined by means of subcarrier multiplexing (SCM) into a single analog signal, which is then transmitted over an optical link. To provide good picture quality, this analog signal must have an SNR much greater than 14 to 17 dB, which is typical for non-return-to-zero (NRZ) signal. To be more precise, cable television engineers use the term “CNR” for RF-modulated signals such as the NRZ signal for SCMs systems and reserve the term “SNR” for baseband signals. For analog TV channels with AM-VSB modulation, the National Association of Broadcasters (NAB) recommends a CNR > 46 dB. For a digital TV channel with QAM-256 modulation and forward error correction (FEC), a typical CNR > 30 dB is required [149].
Direct-Detection Systems for Fiber-Access Networks
Published in Zhensheng Jia, Luis Alberto Campos, Coherent Optics for Access Networks, 2019
Luis Alberto Campos, Junwen Zhang, Mu Xu
In the shorter access distances of analog optical links (<40 km), received optical power levels are high and the dominant source of noise is relative intensity noise or RIN. RIN dominates over shot noise and thermal noise at receive levels greater than 0 dBm. It also contributes to the limitation in signal-to-noise ratio (SNR) and dynamic range.
Maximizing capacity, flexibility and efficiency in G-PON networks using VCSEL-based OOK and 2/4-PAM formats
Published in Journal of Modern Optics, 2019
G. M. Isoe, A. W. R. Leitch, T. B. Gibbon
In a typical optical fibre link network without forward error correction (FEC), the bit error rate (BER) for error free transmission must remain below 10−12. However, in IM/DD systems, the main noise sources are receiver thermal noise and laser relative intensity noise (RIN) (17). In a DD system the electrical signal current I is proportional to the optical signal power P across the photodiode receiver responsivity RPD and can be represented as I = P RPD. For an OOK modulation format, the BER can be expressed as (17): where I0, I1, and Ith are the currents at bit ‘0’, bit ‘1’ and the decision threshold respectively. The optical power levels corresponding to the ‘0’ and ‘1’ levels are denoted by P0 and P1. The optical modulation amplitude (OMA) is therefore given as OMA = P1 − P0
Spatial diversity for QAM OFDM RoFSO links with nonzero boresight pointing errors over atmospheric turbulence channels
Published in Journal of Modern Optics, 2019
M. P. Ninos, H. E. Nistazakis, E. Leitgeb, G. S. Tombras
By substituting (2) into (3), we obtain the following expression for the output current, im(t,I), of each individual diversity branch, (3,6): where stands for the dc value of the received photocurrent in the mth diversity branch, ρm is the responsivity of each PD, while nopt,m represents the optical link noise with zero mean and variance N0/2, with Ν0 being, (3,5–7): where KB is the Boltzmann’s constant, T stands for the temperature, F is the noise figure of the receiver, RL the load resistor at the PD, q is the electron charge and RIN is the relative intensity noise process which is a function of the square of the optical power, (1–3,6,7).
Data erasure in Fabry–Perot Diode Lasers: effects of facet reflectivity
Published in Journal of Modern Optics, 2020
The results also demonstrated reverse behaviour when compared with lower facet reflectivity results for reflectivity values bigger than 25% independent from applied biased current, due to the low injection locking spectrum. Figure 4 shows the power-to-current response of injection locked (CW-injected) FPLD at different facet reflectivity levels. Injection-locked FPLD effectively suppresses relative intensity noise. When FPLD was injection locked with a laser source, the reflectivity values between 0.2% and 7% demonstrate reverse behaviour compared with free-running FPLD at 0 dB .