Tunable lasers

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Tunable lasers

• The tunable laser could be set to any desired
  wavelength either in the factory or in the field
  by a software command.
• The performance parameters are
• Power
• Spurious mode suppression
• Wavelength stability
• Life time

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Development of monolithic tunable diode lasers

• Significant effort to develop DBR laser marks
  the develop ment of todays monolithic diode
  lasers.
• DBR laser incorporates separate active and
  passive grating reflector regions.

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• Some works included vertically integrated twin
  guide structures to separate active and passive
  DBR regions, but it has inherent limitations.
• Earlier works were not inteneted for wide
  tunability but to develop DBR lasers that could
  be integrated with passive waveguides for
  monolithic coupling to other integrated optical
  components.
• First concentrated effort to develop monolithic
  tunable lasers was carried out at Bell Labs.
• Two and three section tunable DBR laser
• It provides a tuning range of 5 to 10 nm.

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• New application and the invention of internet
  demanded more band width and this led to the
  development of VCSELs and widely tunable lasers.
• Various configurations employed for thw
  development of widely tunable lasers are
• Configurations employing two multielement mirrors
  and vernier tuning enhancement structure
• Y-branch configurations
• SGDBR laser
• It is the first monolithic device to tune over a
  wavelength region of 30nm or more.

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• The laser operates at a wave length where a
  reflection peak from each mirror coincide.
• Since the peak spacing are different only one
  pair of peaks can line up at a time.
• The peaks are spaced by