J. Hou

7 W all-fiber supercontinuum source

Combine a section of photonic crystal fiber and a picosecond fiber laser to realize an all-fiber supercontinuum source. The picosecond laser exhibits 20 W average output power, 14 ps pulse duration at 480MHz repetition rate. Approximately 7 W supercontinuum with over 1100 nm spectral range is obtained with an optical-optical conversion efficiency of 34%. Further improvements for higher average power are discussed in this paper.

Flat supercontinuum generation covering C-band to U-band in two-stage Er/Yb co-doped double-clad fiber amplifier

Supercontinuum generation in the gain fiber in two-stage nanosecond pulse Er/Yb co-doped double-clad fiber amplifier had been demonstrated for the first time to our knowledge instead of the conventional method in which nonlinear fiber was pumped by lasers. The Er/Yb co-doped double-clad fiber acts as the gain media and nonlinear media. This route reduces the splice between fiber laser and nonlinear fiber. The supercontinuum was achieved with spectrum range from 1530 nm to beyond 1700 nm at 6 W output power covering the total C-band to U-band. From the analyzing of the spectra at different stages in the amplifiers, it can be found that it is the modulation instability in the anomalous dispersion regime that initiates the supercontinuum gereration.

Combined supercontinuum source with >200 W power using a 3 × 1 broadband fiber power combiner.

We report an incoherently combined near-infrared supercontinuum (SC) source with >200u2009u2009W output power using a 3×1 broadband fiber power combiner. A broadband fiber power combiner is designed and theoretically investigated. The power transmission efficiencies of light at different wavelengths of the combiner are calculated, and the combiner is verified to be capable of combining broadband sources efficiently. Then a combiner is fabricated. Three ∼70u2009u2009W near-infrared SC sources are constructed and then, using the combiner, a >200u2009u2009W near-infrared SC source is obtained. Conclusively, using incoherently combining method we can obtain a high-power SC source, and the thermo-management can be realized easily. We believe that this is a suitable method to obtain a higher-power SC source.

Passively mode-locked fiber ring laser using semiconductor saturable absorber mirror

We experimentally demonstrate a fiber laser passively mode-locked by a semiconductor saturable absorber mirror (SESAM) in a ring cavity. A pulse series with a temporal width of 1 ns is generated at a repetition rate of 12.3 MHz. With careful polarization adjustment, the pulse width decreases, the peak power increases and the spectral sidebands are formed in the optical spectrum. The reason of the phenomenon above has been analyzed. In addition, the characteristic of the pulse with different length of the Er3+ Doped Fiber (EDF) is studied and the results show that it is reabsorption that causes the laser to shift to longer wavelength direction when the EDF length increases.

Visible supercontinuum generation in tapered photonic crystal fiber pumped by picosecond pulse at 1064 nm

Short photonic crystal fibers (PCFs) with different tapered waist diameter are made to extend the continuum spectrum in the visible range. The diversification of output continuum spectrum with the diameter of the tapered waist is experimentally observed. An all fiber visible supercontinuum source with 1.88 W output is demonstrated in our experiments. To the best of our knowledge, it is the highest all fiber visible supercontinuum generation in tapered PCF, pumping by picosecond pulse at 1064 nm. The suitably designed short tapered PCF can extend the visible spectrum, while, how to preserve the tapered waist is crucial for the all fiber visible supercontinuum source in the practical applications.

Ultra-broadband dispersion measurement of photonic crystal fiber based on supercontinuum pulses

We present an ultra-broadband dispersion measurement method for photonic crystal fiber (PCF) based on Michelson interferometer and supercontinuum pulses. A PCF with hole diameter and pitch, 2.17εm and 3.47εm respectively, is measured. The measured dispersion coefficients are well in agreement with the simulation results of the same fiber.

Cascaded synchronous terahertz optical parametric oscillations in a single MgO:PPLN crystal

We present a synchronously pumped optical parametric oscillator (OPO) based on a single MgO-doped periodically poled lithium niobate crystal (MgO:PPLN) delivering high-repetition-rate picosecond idler output in the mid-infrared. At high power levels, cascaded optical parametric oscillations are observed, from which the forward and backward idler waves are generated in the terahertz (THz) spectral region. We demonstrate the cascaded processes involving THz-wave generation and make explanations for the highorder cascaded optical parametric processes. The cascaded terahertz optical parametric oscillations in a synchronously pumped optical parametric oscillator are reported for the first time to the best of our knowledge.

All-fiber picoseconds MOPA laser with a narrow spectrum output

Abstractwe report an all-fiber picoseconds MOPA laser with a narrow spectrum output in this paper. The repetition rate of the seed source is increased to ∼1 GHz with a unique all-fiber device to suppress nonlinear effects, and a small core gain fiber is used in the power amplifier to support the less transverse mode. Three cascaded amplifiers are adopted to amplify the signal light, and the maximum output power is 30 W with an optical conversion efficiency of 73.9%. The 6 dB spectral linewidth just extends from 0.89 nm of the seed to 1.34 nm at the max output.

Mid-infrared supercontinuum generation in Arsenic Trisulfide microstructured optical fibers

The dispersion characteristics of Arsenic Trisulfide As2S3 chalcogenide glass were analyzed and a kind of As2S3 microstructured optical fiber was designed to shift the zero dispersion wavelength from longer than 4 µm to around 2 µm. The supercontinuum generation in the designed fiber with selected pump wavelengths and pulse durations were simulated through numerically solving the Generalized Nonlinear Schrödinger Equation. The results reveal that the broadest supercontinuum covering 1.1 µm to 5.5 µm can be obtained with pump laser with duration 150 fs centered at 2.0 µm which is slightly longer than the first zero dispersion wavelength. When the pump wavelength is around the zero dispersion wavelength apparent dispersive waves which are significant for spectral broadening can be observed.

The exact simulation of visible supercontinuum generation pumped by a 400W continuous wave fiber laser

We achieve a surprisingly exact agreement between the simulation results and the experimental observations (J. C. Travers et al. Opt. Express 16, 14435-14447(2008)) of visible supercontinuum (SC) generation pumped by a 400W single mode continuous wave (CW) fiber laser. The propagation of CW field in photonic crystal fibers (PCF) is numerically simulated by solving the generalized nonlinear Schrödinger equation with the adaptive split-step Fourier method for high accuracy; moreover, we apply the method of averaging the generated spectra in many simulations to approach the experimental results. Our simulations confirm that the extension of SC toward short wavelengths is due to the trapping of dispersive waves by redshifted solitons.