Optical MIMO Multi-mode Fiber Transmission using Photonic Lanterns

Andreas Ahrens, André Sandmann and Steffen Lochmann

Hochschule Wismar, University of Applied Sciences: Technology, Business and Design,

Philipp-Müller-Straße 14, 23966 Wismar, Germany

Keywords:

Multiple-input Multiple-output Transmission, Optical MIMO, Photonic Lantern, Singular-value Decomposi-

tion.

Abstract:

Within the last years the multiple-input multiple-output (MIMO) technology has attracted increasing interest

in the optical ﬁber community. Theoretically, the concept of MIMO is well-understood and shows some

similarities to wireless MIMO systems. However, practical implementations of optical components are in the

focus of interest. Optical couplers have long been used as passive optical components being able to combine

or split single-input single-output (SISO) data transmissions. They have been proven to be well-suited for

the optical MIMO transmission despite their insertion losses and asymmetries. Nowadays, next to optical

couplers, photonic lanterns (PLs) have attracted a lot of attention in the research community as they offer the

beneﬁt of a low loss transition from the input ﬁbers to the modes supported by the waveguide at its output. In

this contribution the properties of a six-port PL are evaluated by measurements with regards to their respective

MIMO suitability. Based on the obtained results, a simpliﬁed time-domain MIMO simulation model, including

PLs for mode combining at the transmitter-side as well as for mode splitting at the receiver-side, is elaborated.

Our results obtained by the simulated bit-error rate (BER) performance as well as by measurements show that

PLs are well-suited for the optical MIMO transmission.

1 INTRODUCTION

The growing demand of bandwidth particularly

driven by the developing Internet has been satisﬁed

so far by optical ﬁber technologies such as dense

wavelength division multiplexing, polarization divi-

sion multiplexing and multi-level modulation. These

technologies have now reached a state of maturity

(Winzer, 2012). The only way to further increase

the available data rate is now be seen in the area of

spatial multiplexing (Richardson et al., 2013), which

is well-established in wireless communications (Tse

and Viswanath, 2005). Nowadays several novel tech-

niques such as mode group division multiplexing or

multiple-input multiple-output (MIMO) are in the fo-

cus of interest (Singer et al., 2008). Among these

techniques, the concept of MIMO transmission over

multi-mode ﬁbers has attracted increasing interest in

the optical ﬁber transmission community, targeting at

increased ﬁber capacity (Foschini, 1996; Singer et al.,

2008; Winzer and Foschini, 2014). The ﬁber capac-

ity of a multi-mode ﬁber is limited by the modal dis-

persion compared to single-mode transmission where

no modal dispersion except for polarization exists. In

theory, the optical MIMO concept is well-described

(Singer et al., 2008). However, the practical realiza-

tion of the optical MIMO channel requires substan-

tial further research regardingmode combining, mode

maintenance and mode splitting (Schöllmann and

Rosenkranz, 2007; Schöllmann et al., 2008; Sand-

mann et al., 2016; Sandmann et al., 2014). Hence,

photonic lanterns (PLs) have attracted a lot of atten-

tion in the research community (Leon-Saval et al.,

2014). Compared to other passive devices used for

mode combining and mode splitting such as optical

couplers, PLs offer the beneﬁt of a low loss transi-

tion from the input ﬁbers to the modes supported by

the waveguide at its output which makes such devices

very attractive for optical MIMO communication.

Against this background, the novel contribution of

this paper is that based on measurements the suitabil-

ity of PLs for mode combining and splitting is studied

by computer simulations.

The remaining parts of this paper are structured

as follows: Section 2 introduces the studied optical

MIMO system based on PLs and shows measured

characteristics of a 6-port PL. Based on these charac-

teristics in section 3 a corresponding electrical MIMO

channel model is derived. The block-oriented and

SVD-based broadband MIMO system is described in

Ahrens, A., Sandmann, A. and Lochmann, S.

Optical MIMO Multi-mode Fiber Transmission using Photonic Lanterns.

DOI: 10.5220/0006394800240031

In Proceedings of the 14th International Joint Conference on e-Business and Telecommunications (ICETE 2017) - Volume 3: OPTICS, pages 24-31

ISBN: 978-989-758-258-5

section 4. The associated performance results are pre-

sented and interpreted in section 5. Finally, section 6

provides the concluding remarks.

2 OPTICAL MIMO

TRANSMISSION

One approach to form an optical MIMO system is

to transmit multiple data signals on different spa-

tial modes through a few-mode or multi-mode ﬁber

(FMF/ MMF). In this work, photonic lanterns (PLs)

are studied in order to transfer the binary information

carried on the LP

mode in n

single-mode ﬁbers

(SMFs) to discrete modes in a FMF and vice versa.

The physical transmission model is depicted in Fig. 1.

The FMF carries n

modes depending on the geomet-

ric as well as the physical structure of the ﬁber and the

operating wavelength. Subsequent to the transmission

through a FMF of length ℓ, the modes are demulti-

plexed to n

SMFs with an inversely arranged PL.

In theory, for transitioning the incident modes of

the SMF to the respective modes carried in the few

mode ﬁber with low loss the condition n

= n

needs to be respected (Leon-Saval et al., 2013). How-

ever, measurements of the transfer characteristic of

the fusion type PL with 6-ports shows quite a notice-

able insertion loss and slight asymmetries between the

different SMF inputs, see Tab. 1. Still, these asymme-

tries are relatively small when comparing to the in-

sertion loss differences of an optical MIMO system

based on offset SMF to MMF splices and fusion cou-

plers as shown in the same table (Sandmann et al.,

2016). Contrary to expectations, the photonic inte-

grated circuit (PIC) type 6-port PL shows the best re-

sults with respect to the insertion loss. Extending a

fusion coupler based system to 6-ports requires the

concatenation of multiple 2-port systems which is ac-

companied by a signiﬁcant insertion loss increase.

Considering the modal behavior, under ideal con-

ditions the PL transfers the signals from each SMF to

a discrete mode in the FMF, see Fig. 2. In contrast,

three spatial intensity patterns measured at the out-

put of the 6-port PL, compare Fig. 3, show that a real

PL excites a combination of modes which are super-

SMFsSMFs

FMF / MMF

Photonic Lantern

ℓ

Figure 1: Multi-mode MIMO transmission model using

photonic lanterns for mode combining and splitting.

imposed in the FMF, e.g. the LP

and LP

modes.

This can be interpreted as cross-talk. In addition to

the cross-talk introduced by the PLs, mode mixing

during the transmission through the FMF occurs due

to micro bends etc. The idea is to apply MIMO sig-

nal processing in order to remove the cross-talk. For

this purpose, the transmission relations are described

in an electrical system model.

ideal

real

LP +LP +...

01 11

LP +LP +...

11 01

SMFs FMF SMFs FMF

Figure 2: Comparing the spatial mode transformation char-

acteristic of a real PL with an ideal PL.

Figure 3: Example of measured spatial intensity patterns at

the output of a fusion type PL using different input SMFs

at an operating wavelength of λ = 1550 nm; the dotted line

represents the 30 µm ﬁber core diameter.

3 ELECTRICAL MIMO

CHANNEL REPRESENTATION

The electrical baseband MIMO channel representa-

tion employing PLs and a FMF is shown in Fig. 4.

Here, the transmitter-side photonic lantern is fed by

the signals a

(t), with µ = 1,..., n

, representing

the optical signals carried on the LP

mode in the

SMFs. Correspondingly, the signals b

(t) represent

the guided spatial modes at the input of the FMF

and c

(t) are the resulting FMF output signals, where

Photonic Lantern

FMF Channel

(t)

Figure 4: Electrical MIMO channel model.

Optical MIMO Multi-mode Fiber Transmission using Photonic Lanterns

Table 1: Insertion loss measurements when launching from different SMF inputs through a fusion type and photonic integrated

circuit (PIC) type 6-port photonic lantern compared to a 2-port fusion coupler based system.

SMF input number 1 2 3 4 5 6

Fusion type PL insert. loss [dB] 6.7 6.7 4.2 4.1 7.0 4.1

PIC type PL insert. loss [dB] 1.7 2.2 1.5 2.2 2.0 1.7

Fusion coupler insert. loss [dB] 0.1 8.1 – – – –

β,κ = 1,.. .,n

. Finally, the receiver-side PL trans-

fers the modes of the FMF to fundamental modes

in the SMFs, represented by the signals d

(t), with

ν = 1,. .. ,n

. For simpliﬁcation purposes and in

order to create the prerequisites for a near lossless

transmission the number of input SMFs n

, the num-

ber of guided modes in the FMF n

and the num-

ber of output SMFs n

are assumed to be identi-

cally. In this work, these numbers are chosen to be

= n

= 2 and therefore only the LP

and

modes can propagate implying a V-number in

range 2.405 < V < 3.832 when transmitting through

a step-index proﬁled FMF. The degenerate modes of

, i.e. LP

11a

and LP

11b

, are summarized.

3.1 FMF Channel

The transmission properties of the FMF are repre-

sented by the model depicted in Fig. 5. In time-

domain, the system characteristics of the FMF chan-

nel are given as follows

(t) = k

(CH)

(t) + k

(CH)

(t − ∆τ/2)

(t) = k

(CH)

(t − ∆τ/2) + k

(CH)

(t − ∆τ) ,

(1)

describing the mode-coupling of the underlying chan-

nel. Herein, the parameter ∆τ describes the differen-

tial mode delay between the fundamental mode LP

and the mode LP

, which is identiﬁed to be ∆τ =

200 ps for the considered ﬁber length of ℓ = 2 km.

The effect of the chromatic dispersion is not ana-

lyzed in this contribution since a zero chromatic dis-

persion wavelength is assumed which is in the region

of 1300 nm. However, for different wavelengths chro-

matic dispersion can be taken into account by a sim-

ple convolution with a Gaussian function. The optical

ﬁeld coupling coefﬁcients k

(CH)

κβ

describe the coupling

from the mode LP

to the mode LP

, from the mode

to the mode LP

and so forth. Since a lossless

transmission through the FMF is assumed, the cou-

pling coefﬁcients have to fulﬁll the following condi-

tion

∑

κ=1



(CH)

κβ



= 1 ∀ β . (2)

. Finally, the receiver-side PL trans-

fers the modes of the FMF to fundamental modes

, with

. For simpliﬁcation purposes and in

order to create the prerequisites for a near lossless

, the num-

and the num-

are assumed to be identi-

cally. In this work, these numbers are chosen to be

and

modes can propagate implying a V-number in

832 when transmitting through

a step-index proﬁled FMF. The degenerate modes of

(t)

ℓ/2

∆τ/2

(CH)

1 1

(CH)

2 2

(CH)

2 1

(CH)

1 2

Figure 5: Underlying FMF channel model of length de-

Figure 5: Underlying FMF channel model of length ℓ de-

signed for two mode propagation (n

= 2).

3.2 Photonic Lanterns

Hereinafter, the mode combining and mode splitting

process conducted by the photonic lanterns is studied.

Considering a (2× 2) PL the corresponding electrical

representation for the transmitter-side PL is shown in

Fig. 6. At the transmitter-side the mapping of the

(t)

(PL,TX)

1 1

(PL,TX)

2 2

(PL,TX)

2 1

(PL,TX)

1 2

Figure 6: Electrical system model of the transmitter-side PL

= n

= 2).

incident LP

modes, represented by the signals a

(t),

by the PL can be described with the corresponding

coupling matrix

(TX)







(PL,TX)

· · · k

(PL,TX)

· · · k

(PL,TX)







, (3)

OPTICS 2017 - 8th International Conference on Optical Communication Systems

(t)

(PL,RX)

1 1

(PL,RX)

2 2

(PL,RX)

2 1

(PL,RX)

1 2

Figure 7: Electrical system model of the receiver-side PL

= n

= 2).

with k

(PL,TX)

βµ

denoting the transmitter-side coupling

coefﬁcients. Having an ideal PL, compare Fig. 2,

the coupling matrix is given by an identity matrix

considering n

= n

. Since the receiver-side PL is

inversely arranged and is assumed to have identi-

cal properties to the transmitter-side PL, the corre-

sponding coupling matrix is the transpose denoted

by (· )

of the transmitter-side coupling matrix, i.e.

(RX)



(TX)



. Here, it is worth noting that un-

der practical assumptions the output LP

modes of

the receiver-side PL appear as superpositions of the

and LP

modes of the FMF as highlighted in

Fig. 2. Having a non-ideal PL, the corresponding

electrical system model is shown in Fig. 7 for the

receiver-side PL. Here, k

(PL,RX)

νκ

denotes the receiver-

side coupling coefﬁcients, being summarized in the

coupling matrix K

(RX)

. Based on the short ﬁber

length, the PL is assumed to be ﬂat in the considered

frequency band. Since no power-loss is assumed, the

transmitter-side PL coupling coefﬁcients are required

to comply to

∑

β=1



(PL,TX)

βµ



= 1 for µ = 1, ... ,n

(4)

and the receiver-side PL coupling coefﬁcients need to

fulﬁll the following condition

∑

ν=1



(PL,RX)

νκ



= 1 for κ = 1,..., n

. (5)

Considering the overall MIMO channel model,

compare Fig. 4, as a black box with two in- and out-

puts the transfer characteristic can be described by the

corresponding MIMO impulse responses g

νµ

(t). In-

cluding pulse shaping and receive ﬁltering function-

ality the overall (2× 2) MIMO transmission model is

depicted in Fig. 8. Rectangular pulses of frequency

= 1/T

are used for pulse shaping and receive ﬁl-

tering, i.e. g

(t) and g

(t) and hence the overall im-

pulse responses h

νµ

(t) are formed as follows

νµ

(t) = g

(t) ∗ g

νµ

(t) ∗ g

(t) , (6)

where ∗ denotes the convolution operator. An ad-

ditional component to be considered is the additive

white Gaussian noise (AWGN) denoted by the term

(t). The sampled overall impulse responses are

used for the broadband MIMO system model, being

described in the next section.

4 BROADBAND MIMO SYSTEM

DESCRIPTION

Considering a frequency-selective MIMO link, com-

posed of n

optical inputs and n

optical outputs, the

resulting electrical discrete-time block-oriented sys-

tem is modeled referring to (Raleigh and Ciofﬁ, 1998;

Pankow et al., 2011) as follows

u = H· b+ n . (7)

Vector b of size (N

× 1) contains the input symbols

transmitted over n

optical inputs in K consecutive

time slots, i.e. N

= K n

. This vector can be decom-

posed into n

input-speciﬁc signal vectors b

accord-

ing to

b =



,.. ., b



, (8)

where (· )

denotes the transpose operator. These

input-speciﬁc signal vectors of size (K × 1) include

the symbols transmitted at the optical input µ for all

time instances k, with k = 1,. .. ,K, as given by



1µ

,.. ., b

kµ

,.. ., b

Kµ



. (9)

The (N

× 1) sized received signal vector u can again

be decomposed into n

output-speciﬁc signal vectors

of the length K + L

, i. e. N

= (K + L

, and

results in

u =



,.. ., u

,.. .,u



. (10)

By taking the (L

+ 1) non-zero elements of the re-

sulting symbol rate sampled overall channel impulse

response h

νµ

(t) between the µth input and νth out-

put into account, the output-speciﬁc received vector

has to be extended by L

elements, compared to

the transmitted input-speciﬁc signal vector b

deﬁned

in (9). The ((K + L

) × 1) signal vector u

received

by the optical output ν can be constructed, including

the extension through the multi-path propagation, as

follows



1ν

2ν

,.. ., u

(K+L

)ν



. (11)

Optical MIMO Multi-mode Fiber Transmission using Photonic Lanterns

(t)

Figure 8: Electrical (2× 2) MIMO transmission model.

Correspondingly, the (N

× 1) sized vector n de-

notes the AWGN after receive ﬁltering with g

(t)

and sampling. Finally, the (N

× N

) sized system

matrix H of the block-oriented system model de-

scribes the symbol rate sampled overall MIMO chan-

nel h

νµ

(t) consisting of the frequency-ﬂat transmitter-

and receiver-side PL models as well as the frequency-

selective FMF model, the transmit and receive ﬁlter.

The channel matrix H is composed as follows

H = H

(RX)

· H

(CH)

· H

(TX)

. (12)

Herein, the (n

(K + L

) × n

K) sized matrix H

(CH)

describes the frequency-selective representation of

the FMF channel, compare Fig. 5, being structured

as follows

(CH)







(CH)

... H

(CH)

· · · H

(CH)







(13)

and consists of n

single-input single-output

(SISO) channel matrices H

(CH)

κβ

. Every of these ma-

trices H

(CH)

κβ

of the size ((K + L

) × K) describes the

+ 1 non-zero elements of resulting symbol rate

sampled impulse response of the FMF channel repre-

sentation including transmit and receive ﬁltering, re-

sulting in:

(CH)

κβ







κβ

[0] 0 · · · 0

κβ

[1] h

κβ

[0] · · · 0

κβ

[2] h

κβ

[1] · · · 0

κβ

] h

κβ

− 1] · · ·

0 h

κβ

] · · ·

0 0 ·· · h

κβ

]







(14)

Since the transmitter-side photonic lantern (PL) is as-

sumed to be frequency-ﬂat it can be described by a

((n

K)× (n

K)) pre-processing matrix

(TX)

= K

(TX)

⊗ I

, (15)

where ⊗ denotes the Kronecker product, K

(TX)

the transmitter-side PL coupling matrix and I

de-

ﬁnes a (K × K) identity matrix. Matrix H

(TX)

is com-

posed of concatenated (K × K) sized diagonal matri-

ces weighted by the corresponding coupling factors

(PL,TX)

βµ

. Correspondingly the receiver-side PL can

be described by a (n

(K + L

) × n

(K + L

)) post-

processing matrix

(RX)

= K

(RX)

⊗ I

K+L

, (16)

with K

(RX)

denoting the receiver-side PL coupling

matrix. The interference, which is introduced by the

off-diagonal elements of the channel matrix H, re-

quires appropriate signal processing strategies.

The MIMO block diagram of the transmission

model is shown in Fig. 9. A popular technique is

based on the singular-value decomposition (SVD) of

the system matrix H, which can be written as

H = S· V· D

, (17)

OPTICS 2017 - 8th International Conference on Optical Communication Systems

transmit vector

receive vector

noise vector

Figure 9: Transmission system model.

where S and D

are unitary matrices and V is a real-

valued diagonal matrix of the positive square roots

of the eigenvalues of the matrix H

H sorted in de-

scending order. In order to remove the interferences

pre-processed symbols b = D· c are transmitted, with

vector c denoting the unprocessed transmit symbols.

In turn, the receiver multiplies the received vector u

by the matrix S

. Thereby,neither the transmit power

nor the noise power is enhanced. The overall trans-

mission relationship is deﬁned as

y = S

(H· D· c+ n) = V· c+ w. (18)

As a consequence of the processing in (18), the

channel matrix H is transformed into independent,

non-interfering layers having unequal gains (Pankow

et al., 2011; Raleigh and Ciofﬁ, 1998; Ahrens and

Benavente-Peces, 2009). In MIMO communication,

singular-value decomposition (SVD) has been estab-

lished as an efﬁcient concept to compensate the inter-

ferences between the different data streams transmit-

ted over a dispersive channel: SVD is able to transfer

the whole system into independent, non-interfering

layers exhibiting unequal gains per layer as high-

lighted in Fig. 10, where as a result weighted AWGN

channels appear.

Analyzing the considered (2× 2) MIMO system,

the data symbols at the time k, i. e. c

and c

are

weighted by the positive square roots of the eigen-

values of the matrix H

H, i.e.

and

The terms w

and w

denote the noise subsequent

to the SVD post-processing. It is worth noting that

the number of readily separable layers is limited by

min(n

). Therefore, in this work the maximum

number of layers is given by L = 2. Based on this

non-interfering layer-speciﬁc transmission model the

bit-error rate performance can be calculated (Proakis,

2000).

1 k

2 k

1 k

2 k

1 k

2 k

1 k

2 k

Figure 10: SVD-based layer-speciﬁc transmission model.

5 PERFORMANCE RESULTS

In this section the BER quality, transmitting through

the (2 × 2) MIMO channel employing PLs for

mode combining and splitting, is studied using ﬁxed

transmission modes with a spectral efﬁciency of

4 bit/s/Hz. The analyzed quadrature amplitude modu-

lation (QAM) constellations are listed in Tab. 2. This

Table 2: Transmission modes.

Spectral Efﬁciency Layer 1 Layer 2

4 bit/s/Hz 16 0

4 bit/s/Hz 4 4

bit allocation approach is combined with a power allo-

cation method that equalizes the signal-to-noise ratios

on all layers and time instances k in a data block for

optimizing the BER performance (Sandmann et al.,

2015).

In order to compare the performance of ideal PLs

to real PLs different cross-talk parameters have been

considered relating to the above described electrical

MIMO channel model. Since both PLs are assumed

to have identical properties in both directions and are

also assumed to be symmetric the PL cross-talk pa-

rameter is deﬁned as follows

(PL)

cross



(PL,TX)



(PL,TX)



(PL,RX)



(PL,RX)



(19)

describing the electrical power transfer. The few-

mode ﬁber channel cross-talk is assumed to be sym-

metric as well as deﬁned by

(CH)

cross



(CH)



(CH)



. (20)

denote the noise subsequent

to the SVD post-processing. It is worth noting that

the number of readily separable layers is limited by

. Therefore, in this work the maximum

2. Based on this

non-interfering layer-speciﬁc transmission model the

bit-error rate performance can be calculated (Proakis,

0 5 10 15 20

-6

-4

-2

10 · log

) (indB) →

BER →

ideal PL p

(PL)

cross

= 0

real PL p

(PL)

cross

= 0.1

Figure 11: BER performance when transmitting with the

(16,0) QAM constellation (dotted lines) and the (4,4) QAM

constellation (solid lines) assuming 10% FMF cross-talk,

i.e. p

(CH)

cross

= 0.1, at a symbol frequency of f

= 1 GHz.

Optical MIMO Multi-mode Fiber Transmission using Photonic Lanterns

0 5 10 15 20

-6

-4

-2

10 · log

) (indB) →

BER →

ideal PL p

(PL)

cross

= 0

real PL p

(PL)

cross

= 0.1

Figure 12: BER performance when transmitting with the

(16,0) QAM constellation (dotted lines) and the (4,4) QAM

constellation (solid lines) assuming 30% FMF cross-talk,

i.e. p

(CH)

cross

= 0.3, at a symbol frequency of f

= 1 GHz.

0 5 10 15 20

-6

-4

-2

10 · log

) (indB) →

BER →

ideal PL p

(PL)

cross

= 0

real PL p

(PL)

cross

= 0.1

Figure 13: BER performance when transmitting with the

(16,0) QAM constellation (dotted lines) and the (4,4) QAM

constellation (solid lines) assuming 30% FMF cross-talk,

i.e. p

(CH)

cross

= 0.3, at a symbol frequency of f

= 5 GHz.

The calculated BER results as a function of the

signal energy to noise power spectral density E

are depicted in Fig. 11, 12 and 13 for different FMF

cross-talk parameter choices, i.e. p

(CH)

cross

, and sym-

bol frequencies f

. In all simulations the number

of symbols per data block and per layer is selected

to be K = 15. Choosing the (16,0) QAM constel-

lation shows the best BER performance results for

all conﬁgurations considering a real PL. The addi-

tional cross-talk introduced by a real PL increases the

MIMO channel correlation and thus the amplitude ra-

tio comparing the singular values of the two layers

increases as well. Therefore, the (16,0) QAM scheme

beneﬁts from the additional cross-talk. In contrast,

the increased asymmetry of singular values impairs

the BER performance choosing the (4,4) QAM con-

stellation as highlighted by the results.

Figure 14: BER performance comparing different cross-talk

parameter choices when transmitting with the (16,0) QAM

constellation at a ﬁxed E

ratio of 10 dB at a symbol

frequency of f

= 1 GHz.

Figure 15: BER performance comparing different cross-talk

parameter choices when transmitting with the (4,4) QAM

constellation at a ﬁxed E

ratio of 10 dB at a symbol

frequency of f

= 1 GHz.

A second study shows the achievedBERs compar-

ing different cross-talk parameter choices, i.e. p

(CH)

cross

and p

(PL)

cross

, for the (16,0) QAM constellation in Fig. 14

and for the (4,4) QAM scheme in Fig. 15 at a ﬁxed

ratio of 10 dB. This study conﬁrms that the

(16,0) QAM constellation beneﬁts from high cross-

talk values whereas the (4,4) QAM constellation

shows a contrary behavior. It should be noted that

0.5 for p

(CH)

cross

as well as for p

(PL)

cross

is the value where

the most cross-talk is introduced into the system. All

in all, the best BER results are achieved with the

(16,0) QAM constellation in combination with high

cross-talk values when considering the studied simu-

lation environment.

OPTICS 2017 - 8th International Conference on Optical Communication Systems

6 CONCLUSIONS

In this contribution photonic lanterns as a mode cou-

pling and splitting device have been analyzed with

regard to their respective MIMO suitability. The es-

tablished time-domain MIMO simulation model has

been proven to be a versatile tool for the optimization

of the overall MIMO transmission performance. It

has been shown that the excitation of different mode

combinations by the PL, which has been interpreted

as cross-talk, does not impair the transmission qual-

ity. In certain constellations this cross-talk can help to

increase the BER performance. All in all, PLs seem

to be well-suited for optical MIMO communication

systems.

ACKNOWLEDGEMENTS

This work has been funded by the German Ministry

of Education and Research (No. 03FH016PX3).

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Optical MIMO Multi-mode Fiber Transmission using Photonic Lanterns