Pump Light Power Research Articles

Differential thermal lensing in extended samples.

We present a new scheme for a pump-probe mode-mismatched thermal lensing experiment aimed at extracting the value of low-absorbing components in the presence of a high-absorbing background. The method allows for the use of large path-length samples. Changes in the background absorption of a column of ethanol of 20 cm of 1% and a pollutant concentration detection limit of 0.04 ppm are obtained when using a pump light power of 34 mW.

Time response of optical switching properties of Sb thin films under focused laser pulses

The time response of optical switching properties of Sb thin films under focused laser pulses is investigated. The results show that the response course can be divided into onset, opening, and closing stages. Formulas for their lengths are given. The onset and opening times decrease with increasing pumping light power density. The closing time is about 150 ns. For optical memory, if the power density of the readout and recording lasers changes from 5×10 9 to 15×10 9 W/m 2 , the onset time changes from 2.5 to 0.30 μs, and the opening time is on the nanosecond scale.

Theoretical analysis of noise transfer in wavelength converter based on cross-gain modulation in semiconductor optical amplifiers

A theoretical model describing noise transfer characteristics of all-optical wavelength converters based on cross-gain modulation in semiconductor optical amplifiers (SOA) is given in this paper. The analytical results show that the noise transfer is related with the input pump light power, the input probe light power, and the internal loss of the SOA. After wavelength conversion, the noise at the on-level of the input signal can be effectively suppressed while that at the off-level is enhanced, the overall effect is that the signal quality is improved. The theoretical model yields a good agreement with the previous experimental results.

Theoretical Study for Wavelength Conversion of Cascaded Second-Order Nonlinearity in Silica Fiber

In this paper, A novel wavelength divison multiplexing (WDM) nets is proposed by use of cascaded second-order nonlinearities (χ(2):χ(2)) in the D-fiber grating after periodically thermal/electric-field poling, and is theoretically analyzed for the first time. The coupled mode equations of the χ(2):χ(2) nonlinearities are derived, and the analytic expressions for the electric-field amplitude of converted light wave and the conversion efficiency η are obtained under the small signal approximation, which are well consistent with numerical calculations. Both analytic expressions and numerical results show that, under the phase matching, η is proportional to the logarithm of the square of pump light power, and the 4th power of the grating length L and the second-order nonlinearity d. The calculated results also show that η and Δλ of this fiber grating can be reached over -17dB and 120nm, respectively. With the increase of L, η increases rapidly while Δλ decreases quickly. The results of simulated calculations and theoretical analysis show that the cascaded χ(2):χ(2) process is different from quasi-phases-matched difference-frequency generation.

Tunable wavelength conversion in a semiconductor-fiber ring laser

A tunable wavelength converter is demonstrated using highly nondegenerate four-wave mixing in a semiconductor-fiber ring cavity with no external pump light and low input signal power requirements. This device allows continuous tuning of both pump and converted wavelengths over the semiconductor optical amplifier gain bandwidth. Results for 11.8-nm down- and 6.9-nm up-wavelength conversion with input signal power as low as -10 dBm have been obtained at 1 Gb/s with less than 1.6-dB power penalty.

Raman amplification in GaP-AlxGa1-xP waveguides for light frequency discrimination

Raman amplification characteristics of the GaP-AlxGa1-xP heterostructure waveguide have been measured by fine tuning the pump light frequency. The Raman gain and the Raman gain bandwidth are 0.03 × 10-6 W-1 cm-1 and 23.5 GHz, respectively. The amplified signal light can be detected even at the pump light power level of 10 mW. This result shows that the semiconductor Raman amplifier is suitable for demodulators based on light frequency discrimination in wideband optical communication systems.

Wavelength conversions between the two silica fibreloss windows at 1.31 and 1.55µm using differencefrequency generation

Wavelength conversions between the two silica fibre loss windows at 1.55 and 1.31 µm have been demonstrated, for the first time, using difference frequency generation (DFG) in a periodically domain-inverted LiNbO3 channel waveguide. The conversion efficiency, which is proportional to pump light power, is –31 dB for a pump light power of only 3.6 mW.

Squeezed Light Generation with 1.064 µm Nd:YAG Laser and 0.85 µm Single-Mode Fiber

Efficient squeezing at low pump light power is demonstrated with a mode-locked 1.064 µm Nd:YAG laser and a fiber ring reflector made of 0.85 µm single-mode fiber. Noise reduction of about 2.0 dB below the shot noise level is observed. The squeezing process by the optical Kerr effect is calculated with a simple model. The experimental results are in good agreement with the calculated ones.

Large nonlinear optical effect in an InGaAs/InAlAs multiquantum well waveguide

All-optical refractive nonlinearity in a passive InGaAs/InAlAs multiquantum well waveguide is evaluated for TE and TM modes at 1.55 μm wavelength and room temperature. A quarter wavelength change in the optical path length is observed at an input pump light power of 6.5 mW for 1.47 μm wavelength in a 960 μm long device. Nonlinear refractive index n2 is evaluated to be 1.2×10−6 and −0.5×10.6 cm2/W for the TE and the TM modes, respectively.

Ratatory power of sodium vapour oriented by laser radiation

In this paper the rotatory power of sodium vapour is studied when laser light is used as pumping as well as analysis light. The possibility of having an analysis light whose frequency may be varied in a range larger than the interval between theD1 andD2 atomic lines allows us to get for the first time the complete shape of the rotation curve and to measure a rotation different from zero even for frequencies very far from the resonance ones. The complete orientation in the vapour caused by the laser pumping-light power permits to obtain very high rotation values. In a cell containing Na and 200 Torr of Ne, we measured, at 185°C, 10°/cm of specific rotation. The dependence of the optical activity on the buffer gas pressure and on the frequency of the pumping light is also studied.