Slow-light based tunable delay and narrowband comb filtering at 2  μm.

Area of Science:

• Photonics and Optical Engineering
• Telecommunications
• Materials Science

Background:

• The 2000 nm wavelength region is increasingly important for optical communications, sensing, and medical applications.
• Key signal processing functionalities for this region, such as tunable delay and filtering, are underdeveloped.

Purpose of the Study:

• To demonstrate tunable delay and tunable narrowband filtering around 2000 nm.
• To enable optical communications and signal processing at 2-micron wavelengths.

Main Methods:

• Utilized stimulated Brillouin scattering (SBS) in a 100 m long SM1950 fiber.
• Demonstrated slow-light based tunable delay by varying pump power.
• Exploited the narrow gain bandwidth of SBS for narrowband filtering.

Main Results:

• Achieved a tunable delay of up to 18.8 ns for a 35 ns pulse, with a maximum gain of 12.6 dB.
• Observed a delay of 1.67 ns/dB at 2000 nm, exceeding the 1 ns/dB typically seen at 1550 nm.
• Successfully filtered individual comb lines with frequency spacing <50 MHz using the narrow SBS gain bandwidth.

Conclusions:

• The demonstration of tunable delay and narrowband filtering at 2000 nm is a significant advancement.
• These functionalities are critical for enabling advanced optical signal processing and control of comb lines in the 2-micron spectral region.