Self-induced frequency scanning and distributed Bragg reflection in semiconductor lasers with phase-conjugate...

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Photorefractive Materials

Background:

• Semiconductor lasers are crucial for various applications.
• Controlling laser frequency scanning is essential for advanced spectroscopy and communications.
• Photorefractive materials offer unique optical feedback mechanisms.

Purpose of the Study:

• To investigate frequency scanning capabilities of a GaAlAs semiconductor laser.
• To explore the use of barium titanate photorefractive ring passive phase-conjugate mirrors for laser control.
• To analyze the effects of beam overlap adjustment on laser frequency spectra.

Main Methods:

• Utilized a GaAlAs semiconductor laser coupled with a barium titanate photorefractive ring passive phase-conjugate mirror.
• Adjusted the overlap of interaction beams within the barium titanate crystal.
• Observed and analyzed the laser's frequency spectrum and scanning behavior.

Main Results:

• Achieved controllable frequency scans over a 10-nm range towards blue or red.
• Demonstrated that beam overlap adjustment dictates scan direction and repetition.
• Observed laser frequency spectrum narrowing from ~10 to 1-3 longitudinal modes due to self-generated distributed feedback.
• Reported similar effects using a total-internal-reflection passive phase conjugate mirror.

Conclusions:

• Barium titanate photorefractive mirrors enable controlled frequency scanning in semiconductor lasers.
• Self-generated distributed feedback effects lead to significant spectral narrowing.
• Passive phase-conjugate mirrors offer a viable method for tuning laser output characteristics.