Pump Light Source Research Articles

Continuous-wave laser pump light sources: new concepts

The relatively short lifetime of rare-gas discharge pump light sources for high-power cw solid-state lasers is caused mainly by vaporized cathode emitter material reacting with the thermally highly loaded quartz wall. The introduction of new bipolar electrodes without special emitter materials mounted on hot-ended molybdenum-cup seals, together with 60-kHz ac operation, makes possible the application of a tungsten halide cleaning cycle within the lamp bulb. This new type of high-power rare-gas pump light source exhibits 20% better radiation efficiency, 20% lower Nd:YAG laser threshold, and considerably extended lifetime.

670 nm semiconductor laser diode pumped erbium-doped fibre amplifiers

A highly efficient Er-doped fibre amplifier pumped by a visible laser diode is reported. Using a 670 nm AlGaInP laser diode as a pump light source and a high NA erbium-doped fibre, the EDFA realised a maximum signal gain of 33 dB at 1535 nm, with a saturated output power of 4 dBm. A maximum gain coefficient of 3.0 dB/mW was achieved for 670 nm laser diode pumping. >

Xenon Flash Lamp Pumped Self-Frequency Doubling NYAB Q-Switched Laser

By using xenon flash lamp as pumping light source and BDN dye film as passive Q-switch or KD* P crystal as active Q-switch, we have, for the first time, realized Q-switching run from 1.06 μm to 0.53 μm in the NdxY1-xAl3(BO3)4 (NYAB) self-frequency doubling laser and obtained MW/cm2 giant pulse output at 0.53 μm wave length. Meanwhile, the green light output energy and pulse duration were measured under the conditions of different resonator lengths and pumpings. The experimental results are in agreement with the numerical solutions of the Q-switching coupling wave rate equations. Moreover, the ways of improving the green laser output peak power are proposed.

All-optical modulation in crystalline organic semiconductor waveguides

We demonstrate all-optical modulation in crystalline organic semiconductor waveguides grown by the ultrahigh vacuum process of organic molecular-beam deposition. Two light beams with wavelengths of 1.06 and 0.514 μm were used as the guided and the pump light sources, respectively. A refractive index change of 5.4×10−5 at 1.06 μm was observed at a pump intensity of 1.0 W/cm2. This large nonlinear effect is attributed to free electron-hole pairs produced by the dissociation of excitons generated by the short wavelength beam. A carrier lifetime of (17±1) μs which determines the modulator switching time is in good agreement with theoretical predictions. To our knowledge, this is the first observation of free-carrier-induced index modulation in crystalline organic waveguides.

Twin N 2 laser for time-resolved absorption spectroscopy and dye laser oscillator-amplifier pumping

A twin N 2 laser system with a variable lasing time correlation is presented. It is proved experimentally that the difference in the lasing time increases in proportion to the difference in gas pressure (2.7 ns per 10 torr). In addition, the pulse to pulse interval can be varied easily from 0 ns to about 30 ns while offering an approximately constant laser pulse energy (around 2 mJ). A high power dye laser light with 0.6 mJ pulse energy can be obtained by using the twin N 2 laser as a pumping light source.

Compact and highly efficient fiber amplifier modules pumped by a 0.98- mu m laser diode

Highly efficient and small-size erbium-doped fibers with a gain coefficient of 4.9 dB/mW and a strained quantum-well-type InGaAs laser diode with a lasing wavelength of 0.98 mu m as a pumped light source. As a result, the module 4*6*1.5 cm, realized a maximum net gain of 33 dB with an electricity consumption of only 175 mW, which corresponds to a drive current of 80 mA. The module consists of four individual components: a pumping laser diode submodule, a wavelength-division-multiplexing-type fiber coupler, a polarization-insensitive optical isolator, and an erbium-doped single-mode fiber coil.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Fiber Raman amplifiers.

Amplification characteristics of fiber Raman amplifiers are reviewed. Simultaneous Raman amplification experiments of wavelength-division multiplexed (WDM) optical signals and a Raman amplification experiment of coherent optical signals using a 1.46 μm high-power semiconductor laser pump light source and an 80km high-Raman-gain optical fiber are described. Simultaneous amplification of WDM optical signals was demonstrated using 1.2Gbt/s and 565Mbit/s, intensity-modulated optical signals in unidirectional and bidirectional configurations with optical gains of 7dB and 6dB, respectively. No significant degradation was observed in any configuration. Raman amplification of coherent optical signals was also demonstrated through a 560Mbit/s FSK optical heterodyne transmission experiment. An optical gain of 7.5dB was obtained without any degradation. The results show that fiber Raman amplifiers can be used in WDM and coherent optical telecommunication systems.

Properties of fiber Raman amplifiers and their applicability to digital optical communication systems

Bit error rate performances of fiber Raman amplifiers both as booster amplifiers and as detection preamplifiers are studied in intensity modulation/direct detection optical communication systems. It is theoretically shown that, in the booster amplifier application, receiver sensitivity degradation due to amplification can be made less than 0.2 dB for signal-to-noise power ratio larger than 20 dB, and thus an allowable transmission line loss can be increased approximately by the value of Raman gain. For detection preamplifier use, receiver sensitivities in the Raman preamplifier system are numerically calculated in terms of minimum detectable signal power at 100-Mbit/s and 2-Gbit/s bit rates. In both bit rates, it is shown that, for a Raman gain greater than 20 dB, minimum detectable signal power can be improved by more than 15 dB over the conventional detection level without Raman amplification. Preliminary experiments are carried out using a 1.32- mu m Nd:YAG laser and a 1.4- mu m laser diode as pump and signal light sources, respectively. The experimental results are in good agreement with theoretical estimations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Brillouin-gain spectra for single-mode fibers having pure-silica, GeO_2-doped, and P_2O_5-doped cores

Brillouin-gain spectra are measured for pure-silica core, GeO(2)-doped core, and P(2)O(5)-doped core single-mode fibers with different index profiles. A narrow-linewidth semiconductor laser operating at 828 nm is used as the pump light source. The spectral shape of the Brillouin gain is found to be strongly related to the refractive-index profiles. The Brillouin linewidths evaluated experimentally are 90 and 215 MHz for a step-index single-mode fiber and a graded-index single-mode fiber, respectively. The Brillouin Stokes shifts depend on the core/clad-ding dopant materials and their concentrations and range from 20 GHz for the P(2)O(5)-doped core fiber to 21.6 GHz for the puresilica core fiber in the 0.8-microm-wavelength region.

Excited emission and self-frequency-doubling effect of NdxY1-xAl3 (BO3)4 crystal

Using dye laser as pumping light source, we have first realized on NYAB crystal the laser self-frequency doubling run from 1.06μm to 0.53μm. The threshold energy is less than 4mJ; conversion efficiency is 6.2%, and the self-frequency-doubling green light output energy is 2.5mJ.

Optical nor gate using diode laser sources

Two diode lasers are employed as probe and pump light sources for an optical NOR gate consisting of a GaAs/AlGaAs multiple-quantum-well etalon. The frequency spectrum of the probe diode laser was found to be influenced by pump-laser injection into the probe laser as well as feedback of the probe laser itself, which can cause erroneous gate operation or a noisy output signal. Both the pump and feedback effects on the probe-laser frequency were eliminated using a Faraday isolator.

Optical nuclear polarization — Targets and sources

The nuclear polarization of3He by optical pumping using discharge lamps is described, as well as attempts (both successful and unsuccessful) to make a polarized3He target. Recent experimental results with a polarized3He target are presented. Experiments to polarize3He using a laser as a pumping light source are described, and the prospects for producing a dense polarized3He target are indicated. The polarization of other nuclei, especially Xe and Kr, by spin transfer from laser polarized alkalis is described.

Energy transfer in flashlamp pumped organic dye lasers

The pumping characteristics of dye lasers using multiple dyes are discussed. It turns out that varying the dye concentration may change considerably the portion of the pump light spectrum which is effective in creating population inversion. Thus the effect of an energy transfer dye depends strongly on the concentration of the lasing dye. Multiple dye systems are shown to have larger tuning ranges than single dye systems, and should exhibit improved tuned linewidth as well as better dye stability. Experimental results are presented for a common dye combination (Rhodamine 6G and Coumarin 6). Measurements were made both by directly mixing the auxiliary dye with the lasing dye, and also by using the auxiliary dye as a fluorescent spectral filter placed between the pump light source and the laser cell; the results are compared.

Spectral Profiles of the 87Rb Pumping Light Source

This paper is concerned with experimental studies of the 87Rb pumping light source, which is composed of a 87Rb lamp and a 85Rb filter cell. Spectral profiles of the pumping light were observed by means of a Fabry-Perot interferometer. Measurements were executed by using ten filter cells which contained 85Rb atoms and various gases (N2, Ar and He) under various pressures. As a result, it became clear that the change of the pumping light spectrum with the filter cell temperature was specific to each cell. When we took note of the ratio and the difference of the two components of Rb D1 line as measures of the filtering effect, the temperature dependence of these values relied on the kind and the pressure of the foreign gas.

Raman gain in liquid‐core fibers

AbstractThe frequency dependence of the gain factor of stimulated Raman scattering was measured using tunable dye lasers as signal and pump light sources. In CCl4 and C2Cl4 peak gain factors of 1.3 × 10−9 cm/W and 1.7 × 10−9cm/W were obtained for the major Raman lines with a frequency shift of ν0 = 458 cm−1 and 447 cm−1, respectively. From the experimental gain factor a threshold power of 0.2 W was estimated for a liquid‐core fiber filled with C2Cl4 (diameter 10 μm and length 1 km).

Gain measurements of stimulated Raman scattering using a tunable dye laser

The gain factor of stimulated Raman scattering was measured quantitatively as a function of frequency using a tunable dye laser and a ruby laser as signal and pump light source, respectively. In methanol a gain factor of 4 x 10 -4 cm/MW and a frequency width of 18 cm -1 was obtained for the strongest Raman line (Δ v R = 2837 cm -1) .

The Expected Performance of an Optical Pumping Light Source, and the Kinetics of Optical Pumping of 23S13He

A practical light source for optical pumping necessarily excites transitions other than those which it is desired should be excited. It is shown that a pumping light source for 23S13He may be characterized by three parameters, which describe the transition rates for Δm = ±1, and 0, transitions under standard conditions. Expressions are derived relating these parameters to the geometry of the light source. The equation which describes the flow of angular momentum into 3He is formulated, using these parameters, the light flux, the lifetime of the metastable atoms, and collisional mixing in the 23P states. This equation is solved to give the polarization which may be attained, and the rate at which the polarization is built up. A modification of this equation is also given, which takes into account moderate trapping of resonance radiation. An expression is also derived which relates the polarization of 3He to the intensity of the scattered pumping light.

Temperature Dependence of Hyperfine Spectrum of Rb D1 Line

This paper deals with the experimental studies of the rubidium (Rb) spectral lamp for the purpose of getting an excellent pumping light source for a Rb gas cell type frequency standard, or for a Rb microwave maser. Some of Rb lamps containing Ne, Ar, Kr, and Ne-Ar as a carrier gas were made by way of experiment. In order to observe the hyperfine spectrum of D1 line, the Fabry-Perot type scanning interferometer was made, which is driven electrostrictively. The hyperfine components of D1 line were resolved successfully. It was observed that the line which is used as a pumping source became intense as the lamp temperature was raised, and it began to be dipped and decrease, however, over the definite temperature. Also observed was that this optimum temperature differs from the temperature at which the integrated intensity of D1 line shows a maximum.

A Polarizer, Using Sodium Nitrate Single Crystal, Designed as Part of an Optical Pumping Light Source

First Page

Blitzlampengepumpte Farbstofflaser

The threshold pumping power required for dye lasers increases with increasing rise time of the pumping pulse. This is shown by experiments and by analog computer calculations based on the assumption that the population of the upper laser level is depleted by transitions into triplet states of the dye molecules. A special flash lamp with a pulse rise time of 300 ns was used as a pumping light source. Pulse form measurements of spontaneous and laser emission from dye solutions pumped by this flash lamp support the above assumption.