A. V. Shubin

Bismuth-doped-glass optical fibers—a new active medium for lasers and amplifiers

Optical fibers with bismuth-doped silicate and germanate glass cores were fabricated by the modified chemical vapor deposition technique (solution and vapor-phase Bi incorporation). The fibers revealed an efficient luminescence with a maximum in the 1050-1200 nm spectral range, FWHM up to 200 nm, and a lifetime of the order of 1 ms.

Bi-Doped Optical Fibers and Fiber Lasers

The current state of the art in infrared Bi-doped fiber laser research is reviewed. The relevant fiber glass compositions and fiber technologies are introduced. Lasers operating on transitions ranging from 1.15 to 1.55 μm occurring in the bismuth active centers and their energy level schemes are discussed on the basis of the spectroscopic properties of these centers. Continuous-wave fundamental-mode power levels ranging from a few mW near 1.55 μm up to 16 W near 1.16 μm and 22 W near 1.46 μm have been demonstrated in recent years.

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.

Germania-glass-core silica-glass-cladding modified chemical-vapor deposition optical fibers: optical losses, photorefractivity, and Raman amplification

Germania-glass-core silica-glass-cladding single-mode fibers (deltan as great as 0.143) with a minimum loss of 20 dB/km at 1.85 microm were fabricated by modified chemical-vapor deposition. The fibers exhibit strong photorefractivity, with type IIa index modulation of 2 x 10(-3). A Raman gain of 300 dB/(kmW) was determined at 1.12 microm. Only 3 m of such fibers is sufficient for constructing the 10-W Raman laser at 1.12 microm with a 13-W pump at 1.07 microm.

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.

1.32 μm mode-locked bismuth-doped fiber laser operating in anomalous and normal dispersion regimes.

We demonstrate a 1.32 μm mode-locked bismuth fiber laser operating in both anomalous and normal dispersion regimes. In anomalous dispersion regime, achieved by using 13 nm/cm linearly chirped fiber Bragg grating, the laser exhibits multiple soliton operation with pulse duration of 2.51 ps. With the net normal cavity dispersion, the single-pulse operation with higher power has been obtained by avoiding the limitations generic to conservative soliton systems.