Brillouin laser spectrometer based on spectral compression
Abstract
We introduce a spectrometer design that uses Brillouin lasing to perform broadband spectral compression. This approach enables the entire C-band (optical frequencies covering 4 THz, or 25 nm) to be compressed into a 230 MHz wide RF spectrum—allowing a 4 THz wide optical spectrum to be monitored continuously using a standard analog-to-digital converter. This technique is based on the linear dependence of the Brillouin frequency shift on optical wavelength. To use this dependence for spectral analysis, we couple the input optical spectrum into a fiber ring cavity where it acts as an optical pump, exciting a frequency-shifted Brillouin lasing spectrum. The Brillouin lasing spectrum is then referenced to a copy of the original optical spectrum using heterodyne detection, converting the Brillouin frequency shift associated with each lasing mode to the RF domain. The narrow linewidth of the lasing modes enables a precise measurement of individual lines with an uncertainty of 28 MHz (0.2 pm) across a 4 THz band at an update rate of 200 Hz. This simple approach, constructed using standard fiber-coupled telecom components, provides an efficient method for high-resolution, broadband spectral analysis.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 01, 2023
- Source ID
- 10.1063/5.0155327
Entities
People
- Brandon Redding
- Joseph B Murray
- Matthew J Murray
Organizations
- United States Naval Research Laboratory