Difference frequency generation based on mass production laser diodes

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Difference frequency generation based on mass
production laser diodes

• M. Takahashi, S. Ohara, T. Tezuka, H.
  Ashizawa,
• S . Yamaguchi and E. Noda

Toshiba Corporation Tokai University
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Contents

• Introduction
• Signal / Pump laser combination and
  characteristics
• Different Frequency Generation
• DFG laser characteristics
• Absorption measurement of N2O
• Conclusion

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• Introduction

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Background
Highly sensitive and selective gas sensing is
required

• Environmental monitoring
• Industrial plant surveillance
• Industrial process control

MIR absorption spectroscopy
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Main advantage of MIR spectroscopy
1. Sensitive 2. Fast response
3. Compact 4. Cost effective
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Purpose of the research

• Realize more compact and cheaper light source for
  MIR spectroscopy

Solution
DFG laser based on mass production laser diodes
980nm laser diode for fiber communication 600-850n
m band laser diode for optical storage
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• Signal / Pump laser combination and
  characteristics

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Pump laser
FBG stabilized 980nm LD for Eb fiber
pumping Maximum output power 100mW
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Pump laser oscillation spectrum
Power (a.u.)
Wavelength (nm)
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Signal Laser
788nm Fabry-Perot laser diode for CD-R Maximum
output power from LD chip 100mW Maximum output
power from pigtailed fiber 10mW
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Signal laser oscillation spectrum
Power (a.u.)
Wavelength (nm)
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Oscillation Wavelength Control

• Temperature
• 0.35 nm/K(5.6 cm-1/K).
• Operating current.

Select absorption line
Wavelength sweep in selected absorption line
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operating current dependence of the oscillation
wavelength
Wavelength (a.u.)
0.16nm(77GHz)
Operating current (mA)
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• Different Frequency Generation

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Difference Frequency Generation by PPMgLN
PPMgLN
L21.3µm,L20mm,t0.5mm,T40?
ws
wi
4mm
wp
DFG Wavelength?i ?p - ?s
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Input-output characteristics of the DFG
Conversion efficiency0.92mW/W2
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• DFG laser characteristics
• Absorption measurement of N2O

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Schematic diagram of the DFG sensor
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50 times averaged Doppler-broadened absorption
spectrum of N2O
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Absorption spectrum of 1ppm N2O
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Conclusion

• We proposed the Difference frequency generation
  laser based on mass production laser diodes.
• A mid-IR power of 0.23 µm and conversion
  efficiency of 0.92mW/W2 were obtained.
• A DFG linewidth of 161MHz was measured using
  absorption measurement of N2O
• We demonstrated 1ppm N2O detection by using the
  proposed DFG laser