Solar pumped Laser

Supervised By: Presented By:

Prof. D.S. Mehta Ajay Singh

Design and Development of Solar pumped Nd:YAG Laser

Typical Nd:YAG Laser

https://en.wikipedia.org/wiki/Laser_construction

Laser Rod(Active Media) Pumping source (flashtubes/

continuous gas discharge lamps/DPSS lasers

Laser Cavity & output coupler Power Supply

1

https://en.wikipedia.org/wiki/Laser_construction

Laser Rod(Active Media) Pumping source (flashtubes/

continuous gas discharge lamps/DPSS lasers

Laser Cavity & output coupler Power Supply

The Sunlight as pumping source 3.5 to 7.0 kWh/m2 per day Broad spectrum Not hazardous like mercury No power supply No dependence on electricity Available everywhere

Source:http://en.wikipedia.org/wiki/Sunlight#/media/File:Solar_spectrum_en.svg)

Typical Nd:YAG Laser1

Design of Solar pumped Nd:YAG Laser 2


Motivation:

Conversion of naturally available light

into laser light

Alternate pumping source for lasers

Ecofriendly system

System with “No power supply”

Low cost, field portable system

Green Photonics

Basic Requirements:

Collection of solar light

Transportation of the light

Laser cavity design

Laser pumping by the light

Oscillation/Amplification

Optimization !!


Motivation:

Fo

ca

l len

gth

Solar concentrator(Fresnel Lens)

Conversion of naturally available light

into laser light

Alternate pumping source for lasers

Ecofriendly system

System with “No power supply”

Low cost, field portable system

Green Photonics


Fresnel Lens concentrator

Focal length : 61cm

Diameter: 46 cm

Fresnel lens mount

Measured spot size~= 7mm

Groove density= 50 g/inch

Index of refraction= 1.49

Substrate=Acrylic

Transmission=92% (400-1000nm)

3



Focal length : 61cm

Diameter: 46 cm

Fresnel lens mount




Substrate=Acrylic


Fresnel LensCollection of solar light3

Focal point



Focal length : 61cm

Diameter: 46 cm

Fresnel lens mount




Substrate=Acrylic


Fresnel Lens

Focal point

Collection of solar light3

Why Fresnel lens ? Much thinner comparable to conventional lens Large aperture and short focal length Captures more oblique light from a light

source Reduces the amount of material required

compared to a conventional lens

Laser rod (The active media)

Neodymium-doped yttrium aluminium garnet (Nd:YAG)Nd:Y3Al5O12

Dopant Concentration: 1 %

Diameter: 5mm

Length: 50mm, 120mm

AR Coating: (R < 0.2% @ 1064 nm)

HR coating : (R >99% @ 1064nm)

Orientation: <111> +/- 5%

Surface Flatness: <λ/10@1064 nm

Damage Threshold: 500mW/cm2

Energy Level Diagram of Nd:YAG

4

Laser rod (The active media)

Neodymium-doped yttrium aluminium garnet (Nd:YAG)Nd:Y3Al5O12

Dopant Concentration: 1 %

Diameter: 5mm

Length: 50mm, 120mm

AR Coating: (R < 0.2% @ 1064 nm)

HR coating : (R >99% @ 1064nm)

Orientation: <111> +/- 5%

Surface Flatness: <λ/10@1064 nm

Damage Threshold: 500mW/cm2

Energy Level Diagram of Nd:YAG

https://www.rp-photonics.com/yag_lasers.html

Nd3+:YAG is a four-level gain medium:

substantial gain even for moderate

excitation [6]

The gain bandwidth is relatively small, but

this allows for a high gain efficiency and

thus low threshold pump power [6].

5

Light Guide

o Glass

o Conical end

o Total internal reflection

o Reflection

o Selective coating

o Other types of LG available

o Fused silica Light Guide

6

Laser rod

Light from concentrator

Light Guide

Laser rod


Cooling System

Water cooling

Attached to Light guide

Laser rod submerged into water

o Glass

o Conical end


o Reflection

o Selective coating



6

Source:http://en.wikipedia.org/wiki/Sunlight#/media/File

:Solar_spectrum_en.svg)

Light Guide

Cooling System

Water cooling

Attached to Light guide

Laser rod submerged into water

o Glass

o Conical end


o Reflection

o Selective coating



6

Laser rod


Water

Work Done So Far…. Fresnel lens mount

Procurement of Fresnel lens

Procurement of Laser rod

Focal length and Spot size measurement

Fabrication of light guide

Cooling system

Cavity design (on going )

7

Work Done So Far…. Fresnel lens mount

Procurement of Fresnel lens

Procurement of Laser rod

Focal length and Spot size measurement

Fabrication of light guide

Cooling system

Cavity design (on going )

Additional work

Light transport using fiber bundle

IR separation using prism

7

Future Work Plan 8

September

• Cavity Design

• Fix the laser rod in the cavity

October

• Inlet/outlet for cooling water

• Modify the light guide !!

November

• Pumping

• Measure and characterize theoutput

Next Semester

• Place output couplers

• Characterize the output

• Optimization

• Redesign

References:

[1]. J. Almeida, D. Liang, E. Guillot, and Y. Abdel-Hadi, “A 40 W cw Nd:YAG solar laserpumped through a heliostat: a parabolic mirror system,” Laser Phys. 23, 065801 (2013)[2]. Joana Almeidaa, Dawei Lianga and Emmanuel Guillotb, Improvement in solar-pumpedNd:YAG laser beam brightness, Optics and Laser technology ,Volume 44,Issue 7,October2012[3]. D. Liang and J. Almeida, Highly efficient solar-pumped Nd:YAG laser, Opt. Express 19(2011) 26399-26405[4]. L. Jing, H. Liu, Y. Wang, W. Xu, H. Zhang, and Z. Lu, “Design and optimization of Fresnellens for high concentration photovoltaic system,” Int. J. Photoenergy 14, 539891 (2014)[5]. http://nextbigfuture.com/2014/10/sola-powered-lasers-for-magnesium.html[6]. https://www.rp-photonics.com/yag_lasers.html[7]. http://fp.optics.arizona.edu/[8]. http://www.fizik.itu.edu.tr/akturks/files/L&P%2014%20laser%20types.pdf[9]. https://en.wikipedia.org/wiki/List_of_laser_types

Thank for your Attention!

Ray Diagram

Critical angle condition:Half angle= Sin-1(n1

2-n22)1/2= 63.44o for Glass

= 57.83o for Water

8

Future work

Plan

September

Cavity Design

Fix the laser rod in the cavity

October

Inlet/outlet for cooling water

Modify the light guide !!

November

Pumping

Measure and characterize the output

Next Semester

Output couplers

Measure the output and characterize

Optimization

Redesign !!

Engineering

Solar pumped Laser