Frequency bistability of a semiconductor laser under a frequency-dependent feedback.

Area of Science:

• Optoelectronics
• Laser Physics
• Nonlinear Optics

Background:

• Semiconductor diode lasers are fundamental components in various optical systems.
• Optoelectronic feedback mechanisms can significantly alter laser dynamics and emission characteristics.
• Bistability, a phenomenon with multiple stable states, is well-studied in optical systems but typically involves intensity, not solely frequency.

Purpose of the Study:

• To investigate the effect of frequency-dependent optoelectronic feedback on diode laser emission.
• To determine if frequency-exclusive bistability can be achieved in an optical system.
• To characterize the operational points and power stability under such feedback conditions.

Main Methods:

• Utilized a semiconductor diode laser.
• Implemented a frequency-sensitive optical feedback loop.
• Coupled the laser to the cesium D2 spectral line using orthogonally polarized light.

Main Results:

• Observed multiple stable operating points for the laser's emission frequency.
• Demonstrated stable power emission concurrently with frequency bistability.
• Confirmed this as the first reported observation of bistability solely in the frequency domain of an optical system.

Conclusions:

• Frequency-dependent optoelectronic feedback can induce unique nonlinear dynamics in diode lasers.
• The study establishes a novel form of optical bistability, localized exclusively in the frequency domain.
• This finding opens new avenues for controlling and utilizing laser frequency stability in advanced applications.