ALL FIBER STIMULATED BRILLOUIN SCATTERING RING

LASERBy Alexander Horne

Southwestern Indian Polytechnic Institute

Mentor: Khawlah Al YahyaeiFaculty Mentor: Dr. Khanh KieuCollege of Optical Science

University of Arizona

Objectives My project main objective was to build a setup for

a Brillouin enhanced ring fiber cavity laser. Brillouin Scattering occurs when light in a medium

(i.e. air or water) interacts with time-dependent optical density variations and changes it energy and path.

The particular medium being used is a ring optical resonator. The difference between this resonator and a linear resonator is that one light round trip goes in one rotation, unlike a linear resonator that just bounces back and forth for one round trip.

Locking was obtained and compared using different laser sources with 1550nm and 1064nm wavelengths.

I will showing the results and evolution of my experiment with Brillouin Scattering and procedure used for combining fiber.

First Layout of experiment (1 of 3)“ Free space alignment”

Vortex 6000 Laser Controller

Vortex II laser ‘1550nm’

Isolator Reflective Mirror Collimator The fiber being

used is Corning SMF-28 for the 1550 nm laser

Power Meter

Fusion splicing Fusion splicing is

the process in which to fuse to fibers together with heat.

A Fusion Splicer is a machine that is use to fuse these fibers and different types of fibers.

This process is used to build the ring resonator setup

The Display

Brown linesIndicate the splice

Secondary Layout (2 of 3) Beside the items from the

first layout. High-speed servo

controller Arbitrary waveform

generator Oscilloscope Optical Spectrum Analyzer At this point, a

Circulator and a coupler were used to build the Resonator that is use to obtain the Brillouin Scattering.

Final Layout (3 of 3) Two different types of

lasers, there are a Newport Vortex II laser (1.5 m), Koheras Laser by NKT Photonics (1.5 m), and a 1 m laser by Lightwave Electronics.

A Piezo Controller for the Koheras laser.

Another waveform generator for the Koheras laser.

Experimental procedures Laser locking

Was obtained using High-Speed Servo Controller for three different lasers: Vortex II Laser with 1550 nm

Koheras Laser with 1550 nm.1 Micron Laser with 1064nm

Picture and Information from the High-speed servo control manual.

Experimental procedures Laser locking

On the Oscilloscope, I observed the shape of the output signal ( laser resonances). I saw the shape of the output laser signal from the photo detector and also you have the function generator output ( which has the triangle shape).

The Oscilloscope shown in figure to the right are of the lasers looking to be locked.

The issue with losing the lock was the background noise and environmental conditions.

Obstacles and Challenges Free space fiber

alignment was not an easy task to begin with.

Environmental conditions (air, sound, temperature variation, and optical table small vibrations) caused issues with laser locking. So to resolve the issue, the experiment was moved to a stationary table.

The vortex laser was noisy and it doesn’t lock for a long time like the other used once.

Results and Analysis‘Free space laser coupling results’ The figure displays the

output and the output after the isolator.

The graph also provides the gradual loss involved before and after the isolator was introduced.

After moving the experiment to a stationary table, locking the lasers became less difficult.

The enhanced laser cavity was able to be focused and adjust with little loss. 0 2 4 6 8 10 12

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Free Space Laser Coupling Results

I PumpPoutIsolator involvedLoss (attentuation)

P/Output (mW)

I/pu

mp (mA)

Result from Spectrum Analyzer The high point

illustrates the laser being locked.

The circle area shows where there is a spike of no acoustic noise that would is interrupting the laser from locking.

Future work Further investigations and experiments should be carried on. For example, how Stimulated Brillouin Scattering is affected by pump power and fiber length.

The idea is to use this for Four Wave Mixing but this research will be important for future optical science students. I know this is just a stepping stone for a bigger picture.

Conclusion and Acknowledgement The research was hard

and learning what Brillouin Scattering was used for.

When I came here, I didn’t even know that LASER was an acronym.

I do plan to take this information back with me and use it as motivation for learning at my institution.

Dr. Khanh Kieu Khawlah Al Yahyaei Dr. Meredith Kupinski Wei Chen CIAN Program UROC program University of Arizona National Science

Foundation through an REU Site under grant #EEC-1004331.