Generation of 400 μW at 17.5 μm using a two-color Yb fiber chirped pulse amplifier

We have demonstrated the generation of 400 μW of power at ~18 μm by difference-frequency mixing the 1038 and 1105 nm from a two-color, chirped pulse amplification Yb fiber system. A two-color seed is selected from a continuum source and amplified to 300 mW of total power in a two-stage Yb fiber amplifier.     

Multi-wavelength fiber ring laser based on a chirped moiré fiber grating and a semiconductor optical amplifier

A simple and cost-effective multi-wavelength fiber ring laser based on a chirped Moiré fiber grating (CMFG) and a semiconductor optical amplifier (SOA) is proposed.Stable triple-wavelength lasing oscillations at room temperature are experimentally demonstrated.The measured optical signal-to-noise ratio (SNR) reaches the highest value of 50 dB and the power fluctuation of each wavelength is less than 0.2 dB within a 1-h period.To serve as a wavelength selective element,the CMFG possesses excellent comb-like ...     

Nonlinear properties of quantum dot semiconductor optical amplifiers at 1.3 μm： errata

The authors regret that one of the coauthors was inadvertently omitted in the previous paper. E. Varene was a member of the Institut fur Festk6rperphysik at the Technische Universitat Berlin and contributed to the results on cross-phase modulation.     

Properties of optical fiber based synchronous heralded single photon sources at 1.5 μm

1.5 μm synchronous heralded single photon source (HSPS) is experimentally demonstrated based on spontaneously four wave-mixing in liquid nitrogen cooled dispersion shifted fiber. Experimental results show that both preparation efficiency and conditional second order correlation function g(2)(0) increase with pump light level. Between the two important parameters, tradeoff should be taken to obtain high quality fiber based synchronous HSPS. A HSPS with preparation efficiency of >60% and g(2)(0)<0.06 is achieved, multi-photon probability of which is reduced by a factor of >16 compared with the Poissonian light sources. Experimental results show a great potential of the fiber based synchronous HSPS for quantum information applications.     

Coherent beam combination of narrow-linewidth 1.5 μm fiber amplifiers in a long-pulse regime

We report what we believe to be the first experimental demonstration of coherent beam combining of two fiber amplifiers in a 100 ns pulse regime using a signal leak between the pulses. Pulses of ～100 W stimulated-Brillouin-scattering limited peak power are combined with 95% efficiency, a residual phase error of λ/27, and no significant beam quality degradation.     

High-average-power, carrier-envelope phase-stable, few-cycle pulses at 2.1 μm from a collinear BiB3O6 optical parametric amplifier

We generate self-carrier-to-envelope phase-stable, 630 μJ pulses, centered at 2.1 μm, with 42 fs (6 cycle) duration based on collinear optical parametric amplification in BiB(3)O(6) at 3 kHz. These pulses are generated through a traveling wave amplifier scheme, and the bandwidth supports 28 fs (4 cycle) pulse duration. Carrier-to-envelope phase stability was measured to be 410 mrad over 10 min or 260 mrad over 35 s.     

High-efficiency optical compression of Ti:sapphire laser pulses at 800 nm using a silver-coated hollow fiber

A 50 cm silver coated hollow fiber with inner diameter of 250 μm and filled with argon has been used to compress optical pulses from a Ti:sapphire laser at 800 nm. Input pulses with energy of 250 μJ and duration of 110 fs were used and compressed pulses with energy of 220 μJ and duration of 20 fs were generated by using a prism compressor. Numerical and experimental results are compared. There is good agreement between the measured beam diameters of the hollow-fiber output pulse and the calculated values obtained from propagation of the HE₁₁ mode into free space. For comparison, a similar uncoated fused-silica hollow fiber was also used to obtain 20 fs compressed pulses with an energy of 190 μJ. Received: 7 September 2002 / Published online: 26 March 2003 RID="*" ID="*"Corresponding author. Fax: +1-780/492-1811, E-mail: mohebbi@ee.ualberta.ca     

Spectral study of a 1.55 μm multimode FP semiconductor laser using the transmission-line laser model

Transmission-line laser modelling is a time-domain technique suitable for simulating large-signal dynamics and complex phenomena in semiconductor lasers. We show that the transmission-line laser model (TLLM) is capable of predicting optical spectra in excellent agreement with the measured spectra of a commercially available 1.55 m Fabry-Perot (FP) laser, providing that scattering centres are introduced to simulate the effect of discrete scattering in or near the active region. The same model is also able to accurately predict the light-current curve, the pulse-modulation response and the relative-intensity-noise spectra of the laser. Thus, the TLLM can be applied to design and optimize short-haul optical communication systems using these commercial FP lasers.     

Photonic generation of power-efficient FCC-compliant ultra-wideband waveforms using semiconductor optical amplifier （SOA）： theoretical analysis and experiment verification

We theoretically design a power-efficient ultra-wideband pulse generator by combining three monocycle pulses with different weights. We also experimentally demonstrate a feasible scheme to generate such power-efficient ultra-wideband waveforms using cross-phase modulation in a single semiconductor optical amplifier. The designed ultra-wideband pulse fully satisfies the requirements for the spectral mask specified by the Federal Communications Commission with high power efficiency. In the experiment, a power-efficient ultra-wideband waveform with a pulse duration of 310 ps is achieved, and the power efficiency is greatly improved compared with that of a single monocycle pulse or a mixture of two monocycles.     

Generation of passively Q-switched fiber laser at 1 μm by using Mo SSe as a saturable absorber

Passively Q-switched ytterbium-doped fiber lasers(YDFLs) incorporating a molybdenum sulfide selenide(Mo SSe)-based saturable absorber(SA) are demonstrated. The modulation depth and saturation intensity of the Mo SSe-based SA are measured to be approximately 25.0% and 0.002 MW∕cm2, respectively, using the twin detector technique. The YDFL's output has a center wavelength of 1038.5 nm with a top pulse width and energy of 1.2 μs and 18.9 nJ, respectively, at a pump power of 333 mW. The Mo SSe-based SA has a good linear optical response, providing significant opportunity for use in applications over an ultra-broadband spectrum, particularly spectroscopy and biomedical diagnostics.     

Absolute frequency spectroscopy of CO2 lines at around 2.09 μm by combined use of an Er:fiber comb and a Ho:YLF amplifier

The low-frequency tail of an octave-spanning supercontinuum (SC) generated by an Er:fiber comb is enhanced by a multipass Ho:YLF amplifier and used in a sum-frequency-generation scheme to obtain absolute referencing of a single-mode Tm-Ho:YAG laser tunable around 2.09 μm. By tuning the comb repetition frequency, the probing laser is scanned across the absorption lines of a CO(2) gas sample and highly accurate absorption profiles are measured. This approach can be readily scaled to any wavelength above ~2 μm.     

Water vapour and carbon dioxide interference in the high sensitivity detection of NH3 with semiconductor diode lasers at 1.5 μm

H₂O and CO₂ interferences with NH₃ absorption lines in the combination band at 1.5 μm are investigated by means of diode laser spectroscopy, in conjunction with a high sensitivity two-tone frequency modulation technique. Two different spectral regions 6685–6700 cm⁻¹ and 6475–6494 cm⁻¹, respectively are analyzed, and the strongest interference free ammonia lines are identified as possible candidates for high sensitivity detection of ammonia traces in air. Detection limits of 4.5 ppm m at 6482.69 cm⁻¹ and 4 ppm m at 6689.56 cm⁻¹ for ammonia in air at atmospheric pressure are demonstrated. In addition, self and air broadening parameters are measured for some of the investigated lines.     

Spectroscopic evaluation of the vibrational coupling of Er3+ ions in phospho-aluminosilicate fibres and an explanation of compositional variations in Er-Yb 1.5 μm amplifier performance

Evidence is presented that erbium will occupy one of two sites in phospho-aluminosilicate glass dependent on the Al : P ratio. Although high energy P=O vibrational modes are created we suggest these are localised and only couple to one type of Er site. Decay rates and Er-Yb amplifier performance are then critically determined by the Al : P ratio.     

Antenna measurements of open-structure Schottky mixers and determination of optical elements for a heterodyne system at 184, 214 and 287 μm

Antenna patterns of open structure Schottky mixers were measured at 184, 214 and 287 μm. For use in a heterodyne detector system the antenna pattern must be matched to the signal beam, for example the astronomical signal of a telescope, and the optically coupled local oscillator beam. The procedure of determining a lens system is described and the successful application in astronomical observations with the Kuiper Airborne Observatory (KAO) is shown.     

Portable optical water-and-oil analyzer based on a mid-IR (1.6–2.4 μm) optron consisting of an LED array and a wideband photodiode

An optical method for measuring the water and oil content using mid-IR (1.6–2.4 μm) LEDs and a wideband photodiode is suggested for the first time. This method is developed based on the absorption spectra of pure water, dewatered oil, and water—oil emulsions (cut oil) with different content of water and uses 10 types of LEDs in the spectral range 1.6–2.4 μm. It is shown that pure water heavily absorbs the LED radiation in the spectral range 1.85–2.05 μm, oil absorbs in the range 1.67–1.87 μm, and the LED radiation with a maximum at 2.20 μm is equally weakly absorbed by water and oil. An optical cell of the water-and-oil analyzer is designed on the basis of a three-element diode array with radiation maxima at 1.65 (detection of oil), 1.94 (detection of water), and 2.2 μm (reference signal) wideband photodiode covering the spectral range 1.3–2.4 μm. A calibration curve is derived that represents the dependence of the water concentration in oil on the amplitude of the reduced signal obtained by processing three signals from the LEDs. This optical method of measuring the water content in oil underlies a portable analyzer making possible online measurements directly in an oil well.     

Electro-optic tuning of a periodically poled LiNbO3 optical parametric oscillator and mixing its output waves to generate mid-IR tunable from 9.4 to 10.5 μm

We demonstrate electro-optic spectral tuning in a pulsed periodically poled LiNbO₃ (PPLN) optical parametric oscillator (OPO) in ns regime. A 3-cm-long LiNbO₃ crystal is segmented in three equal sections; the outer sections are periodically poled. The center segment is of single domain whose refractive index is changed by electro-optic effect. Applying voltage from 0 to −5000 V, the OPO signal and idler waves are tuned from 1.932 to 1.912 μm and 2.368 to 2.40 μm, respectively. The signal and idler waves obtained are difference-frequency-mixed in a 10 mm long AgGaS₂ crystal to produce mid-IR tunable from ∼10.5 to ∼9.4 μm, which matches the tuning range of a CO₂ laser.     

Design of a spectrum-periodized polymer optical filter using arc-type Mach–Zehnder interferometer and <Emphasis Type="Italic">N</Emphasis>th order phase-generating couplers

We proposed a kind of polymer arc-type Mach–Zehnder interferometer (MZI) optical filter by employing two parallel cascaded Nth-order phase-generating couplers (PGCs). To realize periodic spectrum response with low insertion loss, a nonlinear least square method was investigated for optimizing PGC structure to satisfy periodic phase compensation (PPC) and insertion loss compensation (ILC) conditions. With the needed wavelength period of 24 nm, design and simulation on five Nth-order PGCs-based filters were performed as N changes from 0 to 4. When N=3, the optimized filter exhibits the most favorable uniform periodic response with the maximum period shift less than 0.3 nm, which is about 1/10 times of that of the traditional filter when N=0, and the insertion loss at the central wavelength of each channel is 1.39–9.98 dB. The PGC’s order N should be properly selected for low optical loss, uniform wavelength period, and feasible optimization complexity. The proposed technique can also be used to design such PGCs-based arc-type MZI filters with any other uniform wavelength period by altering the radius-difference between two arc-type MZI waveguides for CWDM networks.