Reproducible modal noise measurements in system design and analysis

Couch, P.; Epworth, R.E.

doi:10.1109/jlt.1983.1072160

Cited by 26 publications

(5 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The normalized frequency V is expressed by means of the wave vector in vacuum k 0 and the indices of the cladding n 2 and the core center n t : V = ak 0 n 1 l/2A~ with Δ=2 n 2 with the expression of <I(r, t)> given by (5). The normalized frequency V is expressed by means of the wave vector in vacuum k 0 and the indices of the cladding n 2 and the core center n t : V = ak 0 n 1 l/2A~ with Δ=2 n 2 with the expression of <I(r, t)> given by (5).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Light Power Fluctuations at the Output End of a Fiber in Partial Coupling with a Detector in Coherent Light

Verrier¹,

Goure²

1987

Journal of Optical Communications

View full text Add to dashboard Cite

Fluctuations of intensity located in the intersection of the end-face image of a graded-index fiber and a circular diaphragm are studied in coherent light. The curve of the signal to noise ratio against the misalignment d shows a discontinuity when the fiber is motionless. To explain this phenomenon, this intensity is calculated by proposing a Gaussian representation of the end-face intensitywhere V is the normalized frequency and a the core radius of the fiber.

show abstract

Section: Discussionmentioning

confidence: 99%

“…have been evaluated [1][2][3][4][5][6][7]. The perfect knowledge of these phenomena is important in optical communications and in light power measurements.…”

Section: Introductionmentioning

confidence: 99%

Light Power Fluctuations at the Output End of a Fiber in Partial Coupling with a Detector in Coherent Light

Verrier¹,

Goure²

1987

Journal of Optical Communications

View full text Add to dashboard Cite

show abstract

“…The modulation index m is defined as (1) Pt(1) Figure 2 shows the respective optical power levels and the corresponding injection current values. The modulation index m is defined as (1) Pt(1) Figure 2 shows the respective optical power levels and the corresponding injection current values.…”

Section: Transmitter-induced Offset Deviationsmentioning

confidence: 99%

<title>Burst-mode receiver and power control for passive optical networks</title>

Hirn¹,

Hiebeler²

1993

Local and Metropolitan Area Networks

View full text Add to dashboard Cite

In passive optical networks using a time-division multiple access (TDMA) scheme, signal bursts from different remote transmitters are interleaved towards a common headend receiver in the upstream direction.Non-uniformities in amplitude and offset of the received bursts are inevitable due to fmite power-control accuracy and because of the varying extinction ratio of the transmitters as a function of optical output power.Additional signal jumps occur, if the attenuation on the optical paths changes as a result of mechanical vibrations or, in multimode fiber systems, due to modal noise. Even if these fluctuations are limited to low frequencies, the power control cannot compensate for them completely.In the following we will describe a receiver concept allowing correct detection of consecutive signal bursts which exhibit high nonuniformity of amplitude and offset. The time constant of the AC-coupled receiver is controlled by the digital circuitry of the headend station. During reception of the synchronisation preambles, it is switched to a low value to allow fast settling of the receiver.Additionally, a power-control system with improved dynamic performance and which can also compensate for fluctuations of optical attenuation will be discussed.The structure of the transmitter and the receiver will be described, and the results of simulations and experiments will be presented. SIGNAL DISTORTION IN PASSIVE OPTICAL NETWORKS (PONs)Passive optical networks exhibit two characteristic properties clearly discerning them from point-to-point links. One is that, due to the splitting loss, their transmission capacity is limited by the power budget rather than by bandwidth constraints. The other peculiarity, which is specific to the time division multiple access (TDMA) scheme usually applied in the upstream direction, is the fact that a single receiver (at the headend) receives interleaved signal blocks from different remote stations, not a continuous signal stream.These different conditions cause signal distortions at PONs to be quite dissimilar from those arising at non-split networks. Noise processes, which are already known from point-to-point fiberoptic applications, will appear with an altered order of intensity, and may be amplified or outweighed by new effects, brought upon by specific properties of the PON. Figure 1 shows, schematically, the receive signal at the headend receiver of the PON prototype we are currently developing. Depicted is a part of the transmission frame. This part consists of consecutive signal envelopes, coming in from different remote transmitters. The envelopes are separated by short (2 bit) guard times to prevent overlapping. Each envelope starts with a 10 bit synchronisation preamble (1010101010), followed by a 6 bit delimiter (111100) and 30 bits of coded data. The coding scheme (4B6B) ensures an equal number of zeros and ones in each envelope. Only one transmitter is active at a time, transmitting either at 'one' or at 'zero' level. Transmitters that are idle are switched off completely...

show abstract

“…In those systems using multimode optical fiber, modal noise becomes a serious problem [1][2][3][6][7][8][9][10][11][12][13][14][15][16], especially in subscriber systems and local area network systems [17]. In those systems using multimode optical fiber, modal noise becomes a serious problem [1][2][3][6][7][8][9][10][11][12][13][14][15][16], especially in subscriber systems and local area network systems [17].…”

Section: Introductionmentioning

confidence: 99%

A New Evaluation Method for Modal Noise in Multimode Optical Fiber Systems

Takahara¹,

Naitoh²,

Hirota³

et al. 1988

Journal of Optical Communications

View full text Add to dashboard Cite

Modal noise becomes a serious problem in multimode optical fiber systems. It is said that there are two main causes for modal noise, one being the optical source and the other fiber vibration. In this paper, the latter cause is discussed.Firstly the speckle fluctuation due to fiber vibration is expressed by a N-th order orthogonal matrix, and the effect of mode dependent loss at a connection point is expressed by coupling coefficients which are approximated by a geometrical progression, and the calculated results using the geometrical progression are in good agreement with Petermann's results. Using above outlined procedure, a carrier-to-noise ratio (CNR) for modal noise based on our model is formulated and the results calculated by our CNR formula are compared with Hill's results.Next, to investigate validities of this new model and of the modal noise estimation procedure, some experiments are carried out and calculated results are in good agreement with experimental ones. Moreover, the calculated modal noise spectra due to this model are in good agreement with the experimental ones.

show abstract

Reproducible modal noise measurements in system design and analysis

Cited by 26 publications

References 7 publications

Light Power Fluctuations at the Output End of a Fiber in Partial Coupling with a Detector in Coherent Light

Light Power Fluctuations at the Output End of a Fiber in Partial Coupling with a Detector in Coherent Light

<title>Burst-mode receiver and power control for passive optical networks</title>

A New Evaluation Method for Modal Noise in Multimode Optical Fiber Systems

Contact Info

Product

Resources

About