Single-frequency Distributed Bragg Reflector Research Articles

Frequency- and intensity-noise suppression in Yb3+-doped single-frequency fiber laser by a passive optical-feedback loop.

The frequency and intensity noise of an Yb3+-doped single-frequency distributed Bragg reflector (DBR) fiber laser are effectively reduced by a simple, passive optical-feedback loop (POFL), which consists of only two optical couplers. The feedback loop, which has resonance with the high reflective grating of the DBR laser and relative long optical path compared to the DBR cavity, results in narrower linewidth and lower relative intensity noise (RIN) in the feedback signal. The RIN of relaxation oscillation is reduced by 20dB from -99.9dB/Hz @ 993 kHz to -119.4dB/Hz @ 192 kHz, and the frequency noise was suppressed at frequencies higher than 1 kHz, with a maximum reduction of about 30 dB from 10 kHz to 100 kHz, which results in a spectral linewidth compression from 3.96 kHz to 540 Hz. Even after one fiber amplification stage, the noise did not increase significantly, and a spectral linewidth well below 1 kHz were also achieved at output power of 10W.

Single-frequency distributed Bragg reflector Nd doped silica fiber laser at 930 nm.

We report a single-frequency distributed Bragg reflector (DBR) fiber laser at 930 nm for the first time, to the best of our knowledge. A ∼2.5 cm long commercial highly neodymium-doped silica fiber was utilized as the gain medium to achieve ∼1.9 mW laser output. The single longitudinal mode operation of this laser was verified by a scanning Fabry-Perot interferometer. This fiber laser is suited for seeding high-power 930 nm narrow-linewidth laser amplifiers, which can be used to generate coherent single-frequency pure blue light through frequency doubling.

976 nm single-frequency distributed Bragg reflector fiber laser

A single-frequency distributed Bragg reflector (DBR) fiber laser at 976 nm was developed with a 2 cm long highly ytterbium-doped phosphate fiber and a pair of silica fiber Bragg gratings. More than 100 mW of linearly polarized output was achieved from the all-fiber DBR laser with a linewidth less than 3 kHz. The outstanding features of this single-frequency laser also include ultralow relative intensity noise and high wavelength stability. This fiber laser is an excellent seeder for high-power 976 nm narrow-linewidth laser amplifiers that can be used for efficient coherent blue-light generation through frequency doubling.

12 W high-brightness single-frequency DBR tapered diode laser

A distributed Bragg reflector (DBR) tapered diode laser with a record optical output power of 12 W and a conversion efficiency of about 44% is presented. The device has a sixth-order surface grating and shows single longitudinal mode emission at 979 nm as well as a nearly diffraction limited beam. At 11.4 W the laser has a lateral beam propagation factor of M 2 1/ e 2 =1.1 with 72% of the power in the central lobe.

A monolithically integrated optical heterodyne receiver

We demonstrate a monolithically integrated optical heterodyne receiver consisting of an input fiber waveguide, a single frequency distributed Bragg reflector (DBR) laser, a multimode interferometer-based 3-dB coupler, and a pair of semiconductor optical amplifier (SOA)/p-i-n modules using a single epitaxial growth based on asymmetric twin-waveguide (ATG) technology. The input signal was coupled into a fiber waveguide and mixed with the DBR local oscillator laser through the 3-dB coupler, and then coupled into the SOA/p-i-n modules for detection. Using this monolithically integrated optical receiver with a wide-band rectifier narrow-band amplifier receiver, a 3-GHz frequency modulated coherent analog optical link is demonstrated.