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We try to obtain stable supercontinuum (SC) generation with broad bandwidth under relative simple pump conditions. We use a 1.3-m-long highly nonlinear tellurite microstructured fiber and pump it by a 15 ps 1064 nm fiber laser. One segment of the fiber is tapered from a core diameter of 3.4 μm to 1.3 μm. For the first time five-order stimulated Raman scatterings (SRSs) are observed for soft glass fibers. SC covering 730-1700 nm is demonstrated with the pump-pulse-energy of several nJ. The mechanisms of SC broadening are mainly SRS, self-phase modulation (SPM) and cross phase modulation (XPM). The tapered segment has two advantages. Firstly it increases the nonlinearity of fiber by several times. Secondly, it acts as a compensation for the dispersion of the untapered segment, and mitigates the walk-off between pump pulse and SRS peaks.

We numerically investigate mid-infrared supercontinuum generation in single mode fluoride fiber pumped by 1.56 μm picosecond fiber lasers. To get high energy conversion efficiency in mid-infrared region, the ratio of power generated in 2.5 ~5 μm range to the total input power for supercontinuum generation is optimized by varying the pulse width, peak power and fiber length. The long wavelength edge of the supercontinuum spectrum can be extended to 4.8 μm in a 100 cm long fluoride fiber pumped by a 1.56 μm fiber laser with a pulse width of 4 ps and a peak power of 100 kW, and the corresponding ratio of power generated in 2.5 ~5 μm range to the total input power is about 44.6%. The spectral broadening is mainly caused by self-phase modulation, stimulated Raman scattering and four-wave mixing. The simulated results show that high average power supercontinuum light source in 2.5 ~5 μm range could be obtained in fluoride fibers pumped by 1.56 μm picosecond fiber lasers.

For a suspended nanowire, the holes surrounding the core are expected to be as large as possible to propagate the light at wavelengths as long as possible. However, the fabrication of nanowire surrounded with large holes is still a challenge so far. In this paper, a method which involves pumping positive pressure of nitrogen gas in both the cane fabrication and fiber-drawing processes, is proposed. A suspended nanowire, with a core diameter of 480 nm and an unprecedented large diameter ratio of holey region to core (DRHC) of at least 62, is fabricated in the length of several hundred meters. Owing to the large holes, the confinement loss of the suspended nanowire is insignificant when the wavelength of light propagated in it is 1700 nm. Additionally, the tube-shaped glass cladding of the suspended nanowire shifts the singlemode cutoff wavelength to 810 nm, which is much shorter than the cutoff wavelength, 1070 nm, of a naked nanowire with the same diameter. A single-mode supercontinuum (SC) generation covering a wavelength range of 900-1600 nm is obtained under 1064 nm pump pulse with the peak power as low as 24 W. A single-mode third harmonic generation (THG) is observed by this nanowire under the pump of a 1557 nm femtosecond fiber laser. This work indicates that the suspended nanowire with large holes can provide high nonlinearity together with single-mode propagation, which leads to interesting applications in compact nonlinear devices.

We demonstrate four-wave mixing based broadband (>68 nm) wavelength conversion and flattened supercontinuum generation spanning from 900 to 2800 nm in a 36-cm long tellurite microstructured fiber which has a high nonlinearity. By reducing the size of air holes of the tellurite microstructured fibers, single mode propagation and small dispersion slope are obtained without the propagation loss enhancement. Our results show that chromatic-dispersion controlled tellurite microstructured fibers are promising candidates for nonlinear applications.

Supercontinuum (SC) generation has the important applications such as broadband light source, optical coherence tomography, ultra-short pulse compression, and optical frequency metrology, etc. Tellurite glass is transparent in the mid-infrared range, and has a higher n 2 than silica glass by at least one order of magnitude. We have fabricated the hexagonally shaped tellurite air-clad fiber with a core diameter of around 1 μm through controlling the temperature field exactly in the process of fiber-drawing. Since the SC generation strongly depends on the chromatic dispersion, which is determined by the microstructure of fiber, it is interesting to investigate and demonstrate such dependence for such a small core fiber in detail. In this work by pumping a positive pressure of nitrogen gas into the holes of preform, we obtained 1 μm core fibers with diameter ratio of holey region to core (DRHC) varied from 3.5 to 20. The dispersion was tailored effectively by the variation of DRHC. Dependences of SC on the microstructure and dispersion were demonstrated. The pump lasers were picosecond and femtosecond fiber lasers. One octave flattened SC generation was obtained for the fibers pumped by 1064 nm picosecond fiber laser with the pulse energy of several hundred pJ. Intense second and third harmonic generations were obtained under the pump of a 1557 nm femtosecond fiber laser. The correlation of dispersion and SC spectra was analyzed. Such tellurite microstructured optical fibers (MOFs) with high nonlinearity and controlled dispersion are significant in nonlinear applications.

We report broad near-infrared soliton source generation in a TeO 2 -Bi 2 O 3 -ZnO-Na 2 O tellurite microstructured optical fiber pumped by a 1557 nm femtosecond fiber laser. A continuous soliton wavelength shift from 1582 nm to 1851 nm was realized through a tellurite microstructured optical fiber as short as 6.5 cm. Experimental results are in good agreement with the numerical simulations using a generalized nonlinear Schrodinger equation. In addition, an analytical description of the Raman response function of tellurite glass is provided, and a Raman contribution factor of 0.51 is obtained from the actual Raman gain spectrum.

A tellurite suspended core nanofiber with extremely large holey region is demonstrated for the first time. A single-mode third harmonic generation is observed under the 1557 nm pump by a femtosecond fiber laser.

Enhanced soliton trapping of dispersive waves in a tapered tellurite microstructured fiber pumped by a 1557 nm femtosecond laser is demonstrated. The short wavelength edge of supercontinuum light is extended from 960 to 600 nm.

An analytical description of the Raman response function of tellurite fiber is provided. The Raman contribution factor f R of 0.51 and Raman time constant of 8.07 fs are obtained from the Raman gain spectrum.

Tellurite air-clad fibers with small hexagonal core and controlled dispersion were fabricated. Dependences of supercontinuum generation, pumped by picosecond pulse, on the microstructure and dispersion of these fibers were demonstrated for the first time.

We report what we believe to be the first demonstration of the second and third harmonics in tellurite microstructured fibers pumped by a 1557 nm femtosecond fiber laser. The intensities of the second and third harmonics are enhanced by increasing the nonlinear coefficient of the tellurite microstructured fiber. By using tellurite microstructured fiber with a core diameter of approximately 2.7 microm, supercontinuum light expanding from 470 nm to 2400 nm could be achieved. The effects of the fiber-core diameter on the flatness of the supercontinuum light are also investigated when pumped at 1557 nm.

For a suspended core nanofiber, the holey region is expected to be as large as possible to propagate the light at wavelengths as long as possible. Additionally, a large holey region is significant for its applications in sensors. However, the fabrication of nanofiber with large holey region is still a challenge so far. In this paper a method, which involves pumping positive pressure of nitrogen gas in both the cane fabrication and fiber-drawing processes, was proposed. A suspended core nanofiber, with a core diameter of around 480 nm and an unprecedented diameter ratio of holey region to core (DRHC) of at least 62, was fabricated in the length of several hundred meters. Owing to the large holey region, the confinement loss of the suspended core nanofiber is insignificant when the wavelength of light propagated in it is 1700 nm. For this fabrication technique, the nanowire length, fabrication efficiency, and the uniformity in the diameter are much superior to those of the nanowires fabricated in other ways. Finally, single mode third harmonic generation was observed by this nanofiber under the pump of a 1557 nm femtosecond fiber laser. This work shows the prospect of fabrication of nanostructured waveguide in glass materials by an inflation technique.

Tellurite highly nonlinear microstructured fibers were fabricated by pumping a positive pressure of nitrogen gas into the holes of cane in the fiber drawing process. By adjusting the pump pressure to inflate the holes of the fiber, the microstructures were reshaped, and the chromatic dispersions were tailored. Two kinds of fiber were fabricated. One is an air-clad fiber with a 1 μm hexagonal core, which is the smallest core in this shape for the air-clad fiber. By changing the inflation pressure, the diameter ratio of holey region to core (DRHC) was changed in the range of 1-20. Fibers with DRHC of 3.5, 10, 20 were demonstrated. By increasing the DRHC, the zero dispersion wavelengths were shifted to the short wavelength and the confinement loss were decreased. Another is a complex microstructure fiber with a 1.8 μm core surrounded by four ring holes. The shape of the microstructure was reshaped so heavily by the inflation pressure that it is obviously different from the original shape in the cane. The correlations among pump pressure, hole size, surface tension and temperature gradient were investigated. The temperature gradient at the bottom of the preform's neck region was evaluated quantitatively. The chromatic dispersion of this fiber was compared with that of a step-index air-clad fiber. It was found that this fiber had a much more flattened chromatic dispersion. Supercontinuum generations were investigated by the pump of a 1557 nm femtosecond fiber laser. Intense third harmonic generations were obtained from the 1μm haxgonal core fiber. Broad and flattened spectrum was obtained from the complex microstructure fiber. This investigations show that, by using a positive pressure to reshape the microstructure and by controlling the fabrication conditions exactly, highly nonlinear soft glass fibers with desirable chromatic dispersion can be fabricated, and such fibers have interesting applications in highly nonlinear field such as THG and SC generation.

We propose a chalcogenide (As 2 S 3 ) core tellurite cladding microstructured fiber with flattened normal dispersion for ultraflat supercontinuum (SC) generation. To realize flattened normal dispersion, the structure parameters are optimized such as the chalcogenide core diameter, the air hole diameter and the distance between the centers of the two neighboring air holes. The ultraflat normal dispersion curve is obtained and the pulse propagation is investigated using a nonlinear Schrodinger equation. It is shown that an ultraflat SC spectrum with deviations less than 4 dB over an octave (from 1400 nm to 3000 nm) can be achieved by the illumination of a pulsed light with a pulse width of 200 fs, central wavelength of 2000 nm and peak power of 1000 W.

We demonstrate wide and flattened supercontinuum generation in zero-dispersion wavelength decreasing tellurite microstructured fibers fabricated by using the tapering method.

We demonstrate ultra-broadband SC generation from UV to 6.28 μm in a 2-cm-long fluoride fiber pumped by a 1450 nm femtosecond laser. ©2010 Optical Society of America.

We demonstrate widely tunable narrowband soliton and dispersive wave source generation (1150-2250 nm) in a highly nonlinear tellurite microstructured fiber pumped by a 1550 nm femtosecond fiber laser.

We shows new potential of tellurite fibers with high nonlinearity as optical signal processing and coherent light generation media by demonstrating applications of stimulated Raman and Brillouin scattering and supercontinuum generation.

A highly nonlinear composite fiber, which has a 1.5 microm chalcogenide glass core surrounded by a tellurite glass microstructure cladding, has been fabricated by the method of stack and draw. A tellurite glass capillary containing a As(2)S(3) rod was sealed with negative pressure inside. Then this capillary and other empty capillaries were stacked into a tellurite glass tube, and elongated into a cane. This cane was then inserted into another tellurite glass jacket tube and drawn into the composite microstructure fiber. The fiber has a flattened chromatic dispersion together with a zero dispersion wavelength located in the near infrared range. The propagation losses at 1.55 microm were 18.3 dB/m. The nonlinear coefficient at 1.55 microm was 9.3 m(-1)W(-1). Such a high nonlinear coefficient counteracts the high propagation losses to a large extent. A supercontinuum spectrum of 20-dB bandwidth covering 800-2400 nm was generated by this composite microstructure fiber.

We demonstrate widely tunable green (528∼542 nm) third harmonics and near infrared (1228∼1867 nm) soliton (or dispersive wave) source generation in tellurite microstructure fibers.

We report what we believe to be the first demonstration of the second, third harmonics and flattened supercontinuum generation in tellurite microstructure fibers pumped by a 1557 nm femtosecond fiber laser.

Tellurite glass microstructure fibers with a 1 microm hexagonal core were fabricated successfully by accurately controlling the temperature field in the fiber-drawing process. The diameter ratio of holey region to core (DRHC) for the fiber can be adjusted freely in the range of 1-20 by pumping a positive pressure into the holes when drawing fiber, which provides much freedom in engineering the chromatic dispersion. With the increase of DRHC from 3.5 to 20, the zero dispersion wavelengths were shifted several hundred nanometers, the cutoff wavelength due to confinement loss was increased from 1600 nm to 3800 nm, and the nonlinear coefficient gamma was increased from 3.9 to 5.7 W(-1)/m. Efficient visible emissions due to third harmonic generation were found for fibers with a DRHC of 10 and 20 under the 1557 nm pump of a femtosecond fiber laser. One octave flattened supercontinuum spectrum was generated from fibers with a DRHC of 3.5, 10 and 20 by the 1064 nm pump of a picosecond fiber laser. To the best of our knowledge, we have for the first time fabricated a hexagonal core fiber by soft glass with such a small core size, and have demonstrated a large influence of the holey region on the dispersion, nonlinear coefficient and supercontinuum generation for such fiber.

In this paper, we demonstrate a widely tunable passively mode-locked fiber laser covering the C or L band with carbon nanotube films. Our results show that the saturable absorber incorporating nanotubes (SAINT) has potential for constructing widely tunable passively mode-locked fiber laser.

Tellurite glasses are known as one of highly nonlinear fiber materials. We shows new potential of tellurite fibers as lightwave signal processing media by demonstrating applications of stimulated Raman and Brillouin scattering, and supercontinuum generation.

Single frequency 1083nm ytterbium fiber master oscillator power amplifier system was demonstrated. The oscillator was a linear fiber cavity with loop mirror filter and polarization controller. The loop mirror with unpumped ytterbium fiber as a narrow bandwidth filter discriminated and selected laser longitudinal modes efficiently. Spatial hole burning effect was restrained by adjusting polarization controller appropriately in the linear cavity. The amplifier was 5 m ytterbium doped fiber pumped by 976nm pigtail coupled laser diode. The linewidth of the single frequency laser was about 2 KHz. Output power up to 177 mW was produced under the launched pump power of 332 mW.

Stimulated Brillouin scattering (SBS) can amplify the light propagating in a direction opposite to the pump light. It has many applications such as optical amplification, lasing, optical fiber sensor, optical phase conjugation, slow light generation and stored light. In the case of slow light generation via SBS, tunable all optical delay lines via SBS using an optical fiber have been demonstrated [1], which shows that SBS delay line is a promising candidate for all-optical buffers in optical communication system. For all the Brillouin slow light systems, time delay is always accompanied by the pulse distortion. To reduce the pulse distortion effects, Brillouin slow light system based on doublet gain lines was suggested by Stenner et al [2]. Very recently, Schneider et al [3] reported zero-broadening Brillouin slow light in an optical fiber while accompanying with large pulse distortion.

We demonstrate a widely tunable ring-cavity tellurite fiber Raman laser covering the S+C+L+U band. A high optical signal-to-noise ratio of over 60 dB for almost all the tunable range is also obtained.

We report what we believe to be the first demonstration of flat supercontinuum generation expanding from 1000 to 2100 nm from a microstructure tellurite fiber pumped by a tunable ultrafast laser source.

We demonstrate highly-efficient Brillouin slow-light-generation in a low loss tellurite fiber. A time-delay of 74 ns is achieved for an input pulse of 40 ns width in a 200 m long fiber with a pump power of 19.7 mW.

Raman spectral bandwidths of tellurite glasses are widened by using Raman active components of suitable concentration in appropriate base glasses. The MoO 6 octahedra were found to have high octahedral distortion; therefore, have high Raman polarizability compared to WO 6 , NbO 6 , and TaO 6 octahedra and PO 4 tetrahedra. This high Raman polarizability enabled broadening of the spectral width up to ∼350 cm -1 while maintaining high Raman scattering intensities. Although similar bandwidths could be achieved using combined generation of WO 6 octahedra and PO 4 tetrahedra, the resultant Raman scattering intensity of such glasses is only half of that could be achievable using MoO 6 . It is shown that the simplest tellurite glass showing wide spectral broadening is a quaternary system comprising a network modifier (BaO or Bi 2 O 3 ) and two Raman oscillators (NbO 6 and MoO 6 octahedra). Using the newly developed gain medium gain flattened S+ C+ L ultrabroadband fiber Raman amplifier are designed by solving the inverse amplifier design problem. The relative gain flatness and the effective bandwidth of new gain medium are better and larger than those of conventional tellurite fibers.

Tellurite glass micro-superspheres (Te-μSSs) were prepared by the surface-tension mold (StM) technique, and their whispering gallery mode (WGM) resonances have been investigated as the first trial to realize an ultra-broadband Raman resonator. Micrometer-sized tellurite glass particles were melted on an optical grade glassy-carbon substrate then cooled to room temperature (StM technique). Resultant Te-μSS possesses a super-spherical shape with high optical transparency. The size of the partly truncated area, resulting from the contact surface with the substrate, can be controlled by the composition of the glass and a microsphere with no truncated area was achieved for a glass with 56TeO 2 -3.5BaO-10.5SrO-8Nb 2 O 5 -4WO 3 -16P 2 O 5 (TBSN-4W-16P) composition. The TBSN-4W-16P μSS was excited at 532 nm, and the WGM resonance emission attributed to broad Raman scattering of the glass itself was observed. The Q value of the μSS was ≈ 5 × 10 3 . It was confirmed that the prepared μSSs possess a sufficiently spherical shape and acted as an efficient WGM resonator. These results predict that the Te-μSS has potential for a novel broadband Raman laser.

In this paper, we investigate simultaneous 853 nm + 1533 nm amplification, and wavelength conversion between 1533 nm and 853 nm in Er 3+ -doped fluoride fiber. Based on our simulation results, simultaneous 853 nm ( 4 S 3/2 - 4 I 13/2 transition) + 1533 nm ( 4 I 13/2 - 4 I 15/2 transition) amplification, and wavelength conversion between 1533 nm and 853 nm can be realized in Er 3+ -doped fluoride fibers with the excitation of a 974 nm laser diode, respectively. Furthermore, we investigate the interactions between 853 nm and 1533 nm amplifications, and discuss their effects on simultaneously 853 nm + 1533 nm amplifier. The crosstalk between 853 nm and 1533 nm signals is very weak because of relatively long lifetime (∼10 ms) of the 4 I 13/2 level. By introducing a cavity for 853 nm or 1533 nm lasing into the system, the possibility of wavelength conversion from 1533 nm to 853 nm or from 853 nm to 1533 nm in Er 3+ -doped fluoride fiber excited at 974 nm is clarified, which can be used as the wavelength converter or optical switch between public (the third window: ∼1533 nm) and local (the first window: ∼853 nm) networks in future networks.

We demonstrate a 22 dB all-fiber amplifier at 546 nm using Er 3+ -doped fluoride fiber by forward upconversion pumping of a 974 nm laser diode. The gain saturation effects and the power conversion efficiency of this amplifier are investigated in detail based on gain characteristics and numerical simulations.

We investigate pulse-broadening effects of zero-gain Brillouin slow-light (ZGBSL) in an optical fiber. The results show that the stored-capacity of ZGBSL is less than that of SBS amplifier-based slow-light system.

In this study, we investigated the performance of slow light generation via SBS or SRS in tellurite glass based on characterization of Raman and Brillouin gain coefficients and an evaluation method of slow light generation we developed. The effects of different heavy metal oxides additions on slow light generation via SRS in tellurite glass are also discussed. Our results show that designed tellurite glass is a promising candidate for slow light generation via SBS or SRS due to its high Raman and Brillouin gain coefficients.

We demonstrate Brillouin lasing in a single-mode TeO(2)-Bi(2)O(3)-ZnO-Na(2)O tellurite fiber. A peak value of Brillouin gain coefficients of 1.6989 x 10(-10) m/W is measured on the basis of gain characteristics. An all-fiber Brillouin laser with a maximum unsaturated power of 54.6 mW at 1550 nm and a slope efficiency of 38.2% are achieved from a 200 m tellurite fiber by employing a ring cavity. In addition, a tunable Brillouin comb tellurite fiber laser is demonstrated.

We demonstrate a 16.5 dB all-fiber optical amplifier at 546 nm using Er 3+-doped fluoride fiber for -30 dBm signal power by forward upconversion pumping of a 974 nm laser diode with power of 225mW.

We report cascaded two-wavelength 853 nm and 1533 nm lasing from Er3+-doped fluoride fiber pumped at 974 nm. A new way to get high efficiency and low noise C-band amplifier is suggested for Er3+-doped fibers with low phonon energy.

We demonstrate a 16.5 dB all-fiber optical amplifier at 546 nm using Er3+ -doped fluoride fiber for -30 dBm signal power by forward upconversion pumping of a 974 nm laser diode with power of 225mW.

We demonstrated passively mode-locked ytterbium and erbium doped fiber lasers operating at 1039 and 1560 nm by using a common gold nanorods (GNRs) saturable absorber (SA). The GNRs with designed aspect ratios were mixed with sodium carboxymethylcelluose to form the GNRs SA film. The film had broadband longitudinal SPR (surface plasmon resonance) absorption from 800 to 1800 nm. By inserting the same film into a ytterbium or erbium doped fiber laser cavity pumped by a 980 nm laser diode, stable passively mode-locked laser operation at 1039 or 1560 nm was achieved for a threshold pump power of ~100 or ~70 mW, respectively. The pulse width, the output power, and the repetition rate of the 1039 nm mode-locked laser were 460 ps, 1.47 mW, and 43.5 MHz for a pump power of ~110 mW, respectively. The corresponding output parameters of the 1560 nm mode-locked laser were 2.91 ps, 2 mW, and 35.6 MHz for a pump power of ~74 mW, respectively. Our results showed that one GNRs SA could be used for constructing broadband mode-locked lasers.

NaYF4: Er3+, Yb3+ nanoparticles (NPs) were synthesized by using a high temperature thermal decomposition approach. Under a 980 nm laser excitation, intense emission at 1.53 μm from NaYF4: Er3+,Yb3+ NPs was obtained. NaYF4: Er3+, Yb3+ NPs-PMMA covalent-linking nanocomposite was prepared by copolymerization of the oleic acid-modified NaYF4: Er3+, Yb3+ NPs and methylmethacrylate(MMA). In this case, the doping mass concentration of NPs in the polymer matrix could be up to 1%, which is 10 times larger than previously published results. We constructed optical waveguide amplifiers with a structure of embedded waveguide using the NPs-PMMA nanocomposite as the core material. For an input signal power of 0.14 mW and a pump power of 400 mW, a relative optical gain of 7.6 dB was obtained at 1540 nm in a 15 mm-long waveguide.

An 1120nm Raman fiber laser pumped Tm3+-doped ZBLAN fiber up-conversion laser was demonstrated with blue output power levels up to 116mW. The effects of the reflectivity of the output coupler mirrors on blue laser were investigated. Based on our experimental results, we also found that there exists a competition between photodegradation and photocuring in the operation of blue fiber laser, which can affect the maximum output power of blue fiber laser greatly.

1083nm single frequency ytterbium fiber laser was demonstrated by introducing loop mirror filter and fiber polarization controller in linear cavity. The loop mirror with unpumped ytterbium fiber discriminated and selected laser longitudinal modes efficiently.

2 KHz single frequency 1083 nm ytterbium fiber MOPA system was demonstrated, the maximum output power was 177 mW. The laser oscillator was a linear fiber cavity with loop mirror filter and polarization controller.

We report the generation of multiple soliton self-frequency shift cancellations in a temporally tailored tellurite photonic crystal fiber (PCF). The temporally regulated group velocity dispersion (GVD) is generated in the fiber by soliton induced optical Kerr effect. Two red-shifted dispersive waves spring up when two Raman solitons meet their own second zero-dispersion-wavelengths in the PCF. These results show how, through temporally tailored GVD, nonlinearities can be harnessed to generate unexpected effects.

Single frequency 1064nm ytterbium fiber laser was demonstrated by introducing loop mirror filter in linear laser cavity. Output power was 18 mW under pump power of 107 mW, the slope efficiency was about 20%.