Triple-wavelength laser from a femtosecond laser directly-written fiber cavity for microwave generation.

We report an all-fiber triple-wavelength single-frequency distributed Bragg reflector (DBR) laser for 1-10 GHz microwave (MW) generation. The DBR cavity contains a non-polarization-maintaining Er fiber and a pair of fiber Bragg gratings (FBGs) made using a femtosecond laser line-by-line (LbL) direct-writing method. Such a configuration combining a short cavity and radial asymmetry leads to frequency locking and phase controlling of multi-wavelength fiber lasers.

Nitrate Sensor Using a Photosensitive Epoxy Bioresin.

Nitrogen management through monitoring of crop nitrate status can improve agricultural productivity, profitability, and environmental performance. Current plant nitrate test methods require expensive instruments, time-intensive labor, and trained personnel. Frequent monitoring of nitrate levels of the stalks in living plants can help to better understand the nitrogen cycle and the physiological responses to environmental variations.

Combined frequency-locking technology of a digital integrated resonator optic gyroscope with a phase-modulated feedback loop.

In the resonator fiber optic gyroscope (RFOG), the conventional laser feedback loop is realized by adjusting the laser central frequency to tracking the resonance point of the resonator. This method generally relies on the laser tuning coefficient and digital-to-analog converter, which inevitably produces quantization error and limits frequency-locking accuracy and gyro resolution. In addition, the output drift caused by low-frequency noise also is a problem with long-term lock-in tests.