S V Firstov

Combined excitation-emission spectroscopy of bismuth active centers in optical fibers

3D excitation-emission luminescence spectra of Bi-doped optical fibers of various compositions were measured in a wide wavelength range 450-1700 nm. Such luminescence spectra were obtained for Bi-doped pure silica and germania fibers, and for Bi-doped Al- or P-codoped silica fibers (at room and liquid nitrogen temperatures). The energy level schemes of IR bismuth active centers in pure silica and germania core fibers were derived from spectra obtained. The energy level schemes similarity of bismuth active centers in these two types of fibers was revealed.For the first time, 3-dimensional luminescence spectra (luminescence intensity as a function of the excitation and emission wavelengths) have been obtained for bismuth-doped optical fibers of various compositions in a wide spectral range (450-1700 nm). The bismuth-doped fibers investigated have the following core compositions: SiO(2), GeO(2), Al-doped SiO(2), and P-doped SiO(2). The measurements are performed at room and liquid nitrogen temperatures. Based on the experimental results, the positions of the low-lying energy-levels of the IR bismuth active centers in SiO(2)- and GeO(2)-core fibers have been determined. Similarity of the energy-level schemes for the two core compositions has been revealed.

Bi-doped fiber lasers and amplifiers for a spectral region of 1300–1470 nm

Bismuth-doped fiber lasers operating in the range 1300-1470 nm have been demonstrated for the first time, to our knowledge. It has been shown that Bi-doped alumina-free phosphogermanosilicate fibers reveal optical gain in a wavelength range of 1240-1485 nm with pumping at 1205, 1230, or 808 nm.

Optical gain and laser generation in bismuth-doped silica fibers free of other dopants

Luminescence emission and excitation spectra of bismuth-doped silica optical fibers free of other dopants have been obtained to construct an emission-excitation map in a wide wavelength range of 400-1600 nm. The main low-lying energy levels of the bismuth active centers in such fibers have been determined. For the first time (to our knowledge), optical gain and lasing have been obtained in such fibers. A gain of 8 dB has been achieved with a pump power of 340 mW, and a cw fiber laser emitting at 1460 nm with an output power of 40 mW and an efficiency of ≈3% has been created.

Laser diode pumped bismuth-doped optical fiber amplifier for 1430 nm band

A 24 dB gain bismuth-doped fiber amplifier at 1430 nm pumped by a 65 mW commercial laser diode at 1310 nm is reported for the first time (to our knowledge). A 3 dB bandwidth of about 40 nm, a noise figure of 6 dB, and a power conversion efficiency of about 60% are demonstrated. The temperature behavior of the gain spectrum is examined.

Bismuth-doped silica-based fiber lasers operating between 1389 and 1538 nm with output power of up to 22 W

An efficient CW bismuth fiber laser operating around 1.46 μm with an efficiency of >50% and an output power of >20 W has been developed on a bismuth-doped GeO(2)-SiO(2) fiber. The laser demonstrates weak dependence of the output power on temperature in comparison with bismuth lasers operating near 1.15 and 1.3 μm. The laser generation has been obtained in the range 1.39 to 1.54 μm. The first linearly polarized bismuth-doped fiber laser at 1.46 μm based on a PANDA-type fiber has been demonstrated.

Bismuth activated alumosilicate optical fibers fabricated by surface-plasma chemical vapor deposition technology

Plasma chemical technology is experimentally applied to the fabrication of a Bi-activated alumosilicate-core pure-silica-cladding fiber preform. To the best of our knowledge, this is the first time this technology has been applied in this way. We measure gain efficiency at pumping by a 1058 nm wavelength Yb fiber laser in a piece of a newly obtained fiber 20 m in length within 100-1200 nm wavelengths band. The gain efficiency reaches as high as 0.2 dB/mW. Bi-activated alumosilicate-core pure-silica-cladding fiber that is not more than 12 m in length serves a basis for a 1 W output power fiber laser emitting at the wavelength of 1160 nm with 8% slope efficiency. We also measure the photoluminescence spectrum and kinetics of Bi centers responsible for laser emission under the excitation of 193 nm wavelength ArF laser pulses.

Efficient Bi-doped fiber lasers and amplifiers for the spectral region 1300-1500 nm

Watt-level Bi fiber lasers have been demonstrated at 1280, 1330, 1340, 1360 and 1480 nm with the maximum output power of up to 10W and with the efficiency of up to 50% for the first time. The bismuth-doped phosphogermanosilicate fiber amplifiers operating within the wavelength range 1300-1500 nm have been developed. The net gain of more than 20 dB at the wavelengths of 1320 and 1440 nm under the 200-300 mW pump power was obtained. The 3 dB bandwidth of the amplifiers was larger than 30 nm, the noise figure being 4-6 dB.

Superfluorescent 1.44 μm bismuth-doped fiber source

The first bismuth-doped superfluorescent fiber source operating at 1.44-μm was developed. At pump power of 200 mW and pump wavelength of 1310 nm, its output signal reaches 57 mW with spectrum width of 25 nm.

Watt-level, continuous-wave bismuth-doped all-fiber laser operating at 1.7 μm

A watt-level all-fiber laser radiating at the wavelength of 1.7 μm in a continuous-wave regime was developed by using bismuth-doped high-germania optical fiber. A maximum slope efficiency of 33% with respect to the launched pump power was achieved. The dependencies of the slope efficiencies of bismuth-doped fiber laser versus the length of active fiber and reflectivity of the output mirror were obtained.

Luminescence and optical gain in Pb-doped silica-based optical fibers

IR luminescence and optical gain in a Pb-doped fiber have been observed for the first time. Absorption, luminescence and pump on/pump off optical gain spectra, as well as luminescence decay time, have been measured in these fibers. Comparison of optical active center characteristics in Pb-doped and Bi-doped fibers of the same composition indicates an essential difference of optical active centers in these two types of fibers.