Bismuth and Erbium Co-doped Optical Fiber for a White Light Fiber Source

doi:10.4236/opj.2013.32B042

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Optics and Photonics Journal, 2013, 3, 175-178

doi:10.4236/opj.2013.32B042 Published Online June 2013 (http://www.scirp.org/journal/opj)

Bismuth and Erbium Co-doped Optical Fiber for

a White Light Fiber Source

Dawei Song1, Jianzhong Zhang1,2*, Shuo Fang1, Weimin Sun1, Zinat M. Sathi2,

Yanhuo Luo2, Gang-Ding Peng2

1Harbin Engineering University, Harbin 150001, China

2School of Electrical Engineering & Telecommunications, University of New South Wales, Sydney 2052, line NSW, Australia

Email: *[email protected]

Received 2013

ABSTRACT

We demonstrate a white light fiber source based on Bismuth and Erbium co-doped fiber and a single 830nm laser diode

pump. The light spectral intensity from 1100 to 1570nm is over -45dBm, which provide ~40dB dynamic range for an

OSA based spectral measurement.

Keywords: Bi/Er Co-doped Fiber; White Light Sources; Optical Spectral Measurement

1. Introduction

Broadband fiber light sources and amplifiers have broad

applications in the areas of optical communications, the

spectral measurements of fiber devices and optical fiber

sensor. Super-Lum-diodes and Er doped fiber based ASE

sources are the main choices and however they are lim-

ited by the spectral bandwidth, normally smaller than

100nm. The super continue fiber light sources have the

broadest spectrum, from 400 nm to 1700 nm, and while

its applications are limited by the comparably higher

price especially for simple device measurement and

sensing application. So the cheap and reliable fiber

broadband sources need to be developed. Bi doped glass

or silica material [1-5] show the broad luminescence and

the low Bi (< 0.02at %) doped optical fiber[6-11] with

low background loss has been developed to expend the

new band window for optical communication and de-

velop the high power laser. However, no Bi doped fiber

based white light source is reported yet and it is difficult

to be realized especially based on a single pump. Here

we demonstrate a white light fiber source based our de-

veloped Bi and Er co-doped fiber [12] and a single cheap

830 nm laser diode pump. Here we achieved the stronger

and applicable broadband light emission, and its spectral

intensity is over -45dBm from 1100 nm to 1570 nm. The

mechanism of the ultra-broadband source is discussed as

well.

2. Experiments and Discussions

The fiber is fabricated by in situ MCVD doping with

concentrations of [Er2O3] ~ 0.01, [Al2O3] ~ 0.15,

[Bi2O3] ~ 0.16, [P2O5] ~ 0.94, and [GeO2] ~ 12.9 mol

%, respectively. The fiber has a numerical aperture NA ~

0.19 and core diameter of 3.2 µm in order to achieve a

cut-off wavelength λco~0.8 µm because of our following

pump laser diode of 830 nm in wavelength. We observe

the backward luminescence spectra of our Bi/Er

co-doped fiber, pumped by an 830 nm laser diode with a

maximum 60 mw power, base on an 810/1310 nm WDM

and an OSA (Agilent 86140B), shown in Figure 1. A

power meter is used to monitor the pump power and the

left pump power.

Broadband fiber light source: The strongest emission

spectrum, based on the 60mw pump and 3.5m long Bi/Er

co-doped fiber, is shown in Figure 2(a). The red and

green curves are corresponding to the measured and re-

covered true spectra, respectively. The true spectrum is

the true emission spectrum that has been modulated by

the 810/1310 nm WDM coupler. The true spectral inten-

sity is over -45dBm from 1100 nm to 1600 nm and over

-50dBm from 900nm to 1100nm. It provides ~40dB dy-

namic measurement range, because of the OSA spectral

measurement limitation of ~-85dBm at the resolution of

10nm, for the broadband spectral measurement of kinds

Pump

OSA WDM

(810/1310)

Splice point

Bi/Er fiber

Power

Meter

*Corresponding author. Figure 1. Experimental setup.

D. W. SONG ET AL.

176

of fiber devices. The broadband emission intensity is limited

by the pump power by hands and it could be enhanced by

using a pump with a higher power and a longer fiber.

Figure 2(b) shows the relationship between the pump

power and relative emission intensity of total spectrum at

the range of 900 nm to 1600 nm. Here the splice loss be-

tween lead-in single mode fiber and our Bi/Er co-doped

fiber is around ~1.5dB because the mode field is not

matched. We measured the spectra every 10min and last

for a few hours. The stand deviation (<0.2dB) of the

broadband spectrum in Figure 2(c) shows its good sta-

bility, which is important for the spectral measurement

application.

Broadband emission observation: First, we measure

the emission spectra excited by tunable laser with a

wavelength range of 1259 nm - 1500 nm (limited by our

Agilent 8164B) and a constant power of 70 uW and the

results are shown in Figure 3(a). There are two obvious

emission band and their central wavelengths are at 1420 nm

and 1530 nm, which come from Bi and Er related color

centers. Second we observe the luminescence spectra of a

section of our Bi/Er co-doped fiber (<10 cm) based on

830nm laser diode with different pump power, shown in

Figures 3(b) and (d). The different increasing speeds of

the spectra at different wavelength can be observed read-

ily. We calculated the increased emission at the different

wavelength areas when increasing the pump power from

0mW to 1mw, from 10mW to 15mW, and from 55mw to

60mw, shown in Figure 3(c). It is obvious that the emis-

sion band at ~1420 nm is excited and saturated first and

the left side emission bands from 900nm - 1200nm come

secondly and saturated later. The careful observation and

analysis of such broadband light spectra is needed and

done based on the more detail emission observation.

Broadband mechanism discussion: The Er irons give

emission to support the C and L band as we expected. Its

emission spectrum is still there because of its inter-shell

structure according to emission observation. The Bi re-

lated Emission covers the band from 1000 nm to 1500

nm. The emission of our Bi/Er co-doped fiber demon-

strated the emission around 1200 nm (Bi related) and 1530

nm (Er related) when pumped at 980 nm, which is dif-

ferent from the case of 830 nm pump. We also observed

the blue- green up-conversion emission, recorded by a

camera and shown in Figure 1, when the pump power is

over a few milliwatts, which also means the broader

spectrum based on our system. We don’t calibrate the

power of this part of spectra because of the spectral limi-

tation of our OSA. We believe that more than two kinds

of Bi related color centers are involved in our Bi/Er

co-doped fiber. Bi-Si related color centers, reported in

[9], correspond to the emission band around 1400 nm,

shown as the blue-line in Figure 3(c). We still find that

the Bi related emission around 1200 nm is related to the

Er concentration closely. The emission near 1200 nm

would become lower when the Er concentration is lower

for the 830 nm pump. It may be caused by the energy

transition between Er and Bi and they maybe form a

combined color centers. It is important to understand the

broadband mechanism and improve the emission effi-

ciency and the further detail experiments are processing,

which expect to be reported at the conference.

Figure 2. (a) Broadband emission, (b) the total emiss ion p ower changed with the pump power, and (c) the standard deviation of the broad-

band spectrum.

D. W. SONG ET AL. 177

Figure 3. (a) Tunable laser based excitation-emission spectra, (b) the emission spectra of a short section of Bi Er co-doped fiber when in-

creasing the 830nm pump power, (c) the increased emission between different pump powers, and (d) the relationship between the pump

power and the emissions at different wavelengths.

3. Discussion and Conclusions

In conclusion, we report a fiber white light source from

1000 nm to 1570 nm based on the Bi/Er co-doped fiber

and a single 830 nm laser diode pump and discuss its

mechanism based on emission observation, which ex-

pects to have applications in the spectral measurements

of optical fiber devices and the optical fiber sensing.

4. Acknowledgements

Authors thank for the support by National Science foun-

dation projects (60907034, 61077063, 11178010 and LBH-

Z10195), China Postdoctoral Science Foundation funded

project (20100480965), Harbin Science foundation (2011

RFLXG004) and the Fundamental Research Funds of the

Central University, China. Authors thank the support by

international science linkages (ISL) project (CG130013)

from the department of industry, Innovation, Science and

Research (DIISR), Australia. An Australian Research

council (ARC) LIEF grant helped to fund the national

fiber facility at UNSW.

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