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Abstract : In a recent development a novel type of in-fiberintrinsic amplifier has been contemplated and designed which is

based on the principle of optics following the RF wave Shape as

envelope. This needs the fiber (SM/MM) to be subjected to a

predesigned RF field of exponentially decreasing magnitude

along the length (15m) of fiber when optical amplitude is found

to follow the RF magnitude. This happens basically due to the

optical nonlinearity (Kerr effect) of fiber material where the

Nonlinear Schriodinger Equation (NLS) contains a nonlinear

term due to Kerr effect where change in refractive index is

proportional to the square of RF electric field in fiber. In

another work, organic liquid like nitrobenzene is found to show

at least 100 times higher kerr constant than optical fiber glass

material and can be successfully used to guide optics through a

coaxial cable with higher nonlinear effects. In the present work aspiral shaped optical guide filled with nitrobenzene which is

excited centrally by an RF line (nearly 8 MHz) over a length of

15 meters is found to amplify incoherent optics in such a

magnitude so that the total illumination of the spirally shaped

nitrobenzene filled glass light gives 100 times greater

illumination than an ordinary modern day light at the same

wattage. This work is in the form of a proposal where part by

part experimental work is done which governs the principle

behind the design of incoherent low wattage optical luminary.

I INTRODUCTION

In an earlier investigation it has been concluded with repeated

experimentation that, a change in RF in the range 1 3 X 104

is visible within the optical fiber due to nonlinear Kerr effect

when the electric field within the fiber is in the permissible

(below dielectric breakdown field) range 106 6 X 106 v/m

[1,2]. But the experiment was performed with 100 metres of

fiber in a single spacing capacitive setup subjected to nearly

200 Volts DC, and AC, 50 Hz. To generate the same order of

field by a micro structure, experiment has been done with RF

(10 50 MHz) current carrying conductors so that the high

frequency magnetic field after focused by ferrite lens cause

induced electric field whose RMS magnitude is of the same

order as above [3,4].

Based on the same principle, an electrical micro circuit is triedto be developed which creates gradually (exponentially)

decreased electric field regions within the fiber. In this process

an RF and optics interaction length of 15m has been created

where RF field decreases exponentially with length of the

fiber. This causes optical power to be amplitude modulated

with RF and thus the output optical power is found to be

increased by 30dB, for our particular design [5].

In another work [4] it has been found that the organic liquid

Nitrobenzene shows at least 100 times higher Nonlinearty

(Kerr Constant) than pure glass of which fiber is made of. The

breakdown voltage for liquid Nitrobenzene is at least 5 times

higher than pure glass. Moreover, Nitrobenzene is transparent

is visible region. Hence

for higher amplification at the same RF electric field range

5x104- 6x106 v/m the power gain is expected to increase by an

order of 10 times than ordinary glass. So if it is required to

amplify the incoherent light to a minimum 3000 watt level

illumination it is more likely to use Nitrobenzene filled glass

tube subject to a high RF field at the order 105 v/m.

II THEORY

To derive the evolution of envelope of optical power we need

to consider nonlinear Schrodinger (NLS) equation [6]:

ujuuNt

u

z

uj

+

=

22

1 222

2

.. [1]

Where, u(z,t) is the envelope of optical power

N is the order of solution, here N = 1

The envelope gradually grows is z direction i.e. along fiber

length.

is the attenuation of fiber, here, = - 0.8 nepers.m -1 2u is

the induced wave within fiber, here the RF electric field.

Here, in equation [1] the first term2t

u2

2

1

represents group

velocity dispersion effects of the fiber.

The second term u2u is the nonlinear term and if u is

considered to be the electric field variation in fiber then

n2

u where n is the change in refractive index withinfiber.

The third term

uj2

represents the effect of energy

loss. If 0 , there is energy lossLet, us now consider the trial solution for NLS as:

)(.),( tSinzCtzu =

Now, using this trial solution is equation [1]; we get relations:

02

E2

2

1=+ [2]

And,2

= .[3]

From equation [2], we get

0E2= .. [4]

Proposal for new optical luminary

Santanu Chakraborty (Ph.D)

A P C Ray Polytechnic,Jadavpur,Kolkata-700032,West Bengal,India

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and, from equation [3], we get

2

=

As 008.0=For an optical amplifier design >>/2 & the design value is

= -0.4

Again, for a overall gain of optical power of 30dB,6ez40e = .

or, 0.4 X z = 6

or, z = 15 meter

Similarly, in equation [4] we put a satisfactory value

1mV

61060E

= .

Hz6

1048

Hz6

1062Hence

=

=

.

.,

Where, is the RF angular frequency.Now, if we consider a fiber (SM/MM) section of 15 meters

and after every 1.5cm along fiber length, the RF field

diminishes by a factor 060e . , then after an interaction

length (between RF and optics) of 15 meters, the output power

is calculated as:

1222

0 .2

= vrR

EP

wave

[5]

Where r : radius of glass tube filled with nitrobenzene = 10 -2m

Where E : average electric field between starting and ending of

interaction length.

waveRnenitrobenze

wave ==

0impedance of fiber media

Where, mFnenitrobenze /10854.860.412=

0 = Permeability of free space

= 217waveR

So, P0 = 3000 Watt

Hence, if we input an optical power of 1W, the output power is

few hundred watts.

In the second part of our theoretical analysis, we deal with the

RF current required at the surface of the ferrite coated 15

meters strip of glass tube. There are 100 sections of glass tube

with 15cm each and each section current is given by:

n060enI

= .

Where In is the current in the nth section. Due to RF current

InSin(2ft) where, f = 2MHz, the magnetic field induces a RFelectric field given by [2,3]:

10.)2(.

2

= mVftCosR

fIAE

nferrite.

[6]

Where R : core dia of glass tube (MM) = 200m

ferrite : permeability of ferrite = 5 X 104

0 : permeability of free space = 1.6 X 10-6 Henry. m-1

A : cross section area of glass tube = 10-3 m2

In : Amplitude of current in nth section of glass tube

And, we need I1 = 5A, to create an electric field of 5 X 105

Vm-1 as calculated from equation 6.

Now, In = 100e-0.06 X n A [7]

III DESIGN OF OPTICAL LUMINARY

Figure (1) shows the proposed optical light of increased

illumination (than modern day light) due to optical

amplification along the spiral glass tube. Like any transistor

amplifier the optical amplifier is based on two basic principles

(1) its total gain (along 15m) must be higher than total loss

through the length i.e. >> /2 (Accepted value =0.4) (2)the condition for sustained oscillation (The RF field

frequency 8.4 MHz) and RF magnitude = 6x106 which

decreases exponentially. This design needs about 5A RF

current through the glass tube containing Nitrobenzene and

this RF current should exponentially decrease along the length

of the spiral tube. This exponentially decrease in RF current

may be achieved with the use of high frequency capacitors

(more than 100 in numbers) along the length of the glass tube

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filled with Nitrobenzene. The contemplation of the design is

based on the desire to achieve a 3000 watt light bulb with

using a 5A RF source and thereby increasing the illumination

power intensity by 100 times. The total RF line is coated with

ferrite to establish an electric field of 106 v/m.

IV RURAL DEVELOPMENT

The most significant cause behind this research is toilluminate those places in the world where electrical

luminaries are not reached. This development is supposed to

be a cost effective rural solution and may be helpful for the

Institution for rural electrification.

V CONCLUSION

Here a new type of optical luminary based on intrinsic optical

amplification has been successfully studied which is

developed on the principle of amplification of optics

through RF electric field of sufficient amplitude and

designed frequency with optical wave in Nitrobenzene filledglass tube over a designed length (15m) of glass tube. This

travelling wave optical luminary is designed to give an

illumination of 3000W intensity. With the increase of active

optical power, the noise power will also increase and the In-

glass tube amplifier coupled with a filter may reduce the noise

power. It is also to be noted that all the current carrying strips

are supplied by the same source with 5000 Watts of power.

Lastly, with the increase of number of sections from 100 to

1000 along fiber length the noise elimination improves. The

work has been supported by A.P.C Ray Polytechnic, Jadavpur,

Kolkata 700 032, authorities who provided all the facilities

to carry out the work.

REFERENCE

1. S.K. Ghosh, S.K. Sarkar, S. Chakraborty, Design

and development of a fiber optic intrinsic voltage

sensor, proceedings IMEKO TC4 International

Symjposium, September 2002, pp 415-419.

2. S.K. Ghosh, S.K. Sarkar, S. Chakraborty, S. Das

High frequency field effect on plane of polarization

in single mode fiber, proceedings, Photonics 2006,

Hyderabad India 2006, A 454 Photo.

3. S. Chakraborty, Report on soliton pluse generationwithin 50m length of SM fiber by high frequency

induced nonlinear intelligent feedback method,

Proceedings IEEE National Conference, Sonepat,

India, March 13-15, 2008, pp -91-94.

4. S. Chakraborty, Report on Organic liquid filled Co-

axial optical waveguide, Proceedings, National

Seminar on recent trend in emerging frontiers of

physical sciences,, B.I.T. Sindri, Dhanbad, India,

Nov: 2-3, 2009, pp 80-84.

5. G. Keiser, Optical fiber communications Mcgraw

Hill, Internaitonal editions, 2000.

6. S. Chakrabroty, In-fiber intrinsic optical amplifier,

Proceedings of Recent Trends in Engineering &

Education, (RTEE), NITTTR, Kolkata, January 28-

29, 2010.