Continuous Wavelength Tuning Research Articles

Increasing the energy efficiency of dye lasers with highly monochromatic radiation

The tunable laser oscillator was built in the traditional manner with transverse pumping [4]. The pump radiation (10% of the total excimer laser power) was focused by a cylindrical lens onto a flow-through 20 mm long cuvette containing the dye solution. A dispersing resonator included a 600 gr/mma diffraction grating, a prism beam-splitter, and a quartz output mirror with Fresnel reflector. Continuous wavelength tuning was achieved by rotating the diffraction grating using a high precision sinusoidal mechanism provided with indicator. The oscillator construction resulted in a line width of approximately 0.01 run and continuous wavelength tuning with the same precision. First, changes in the spectral and energy characteristics were studied for previous studies, as well as for a host of new dyes from terphenyl, oxazole, pyrazolynyl, and coumarin classes. The laser power was recorded with a IMO-2N meter, and the wavelength with a KSVU-23 spectrum analyzer. All the characteristics were taken under identical conditions. Ethyl alcohol was used as a solvent. In order to achieve the maximum efficiency of pump radiation conversion, the dependence of laser power on dye concentration at a wavelength near the center of the lasing region was determined. Then, using the determined optimum concentration, the dependence of radiation power as a function of wavelength was measured. The basic results of the measurements are presented in Table i. As can be seen from the data presented, the collection of organic dyes used permitted tunable lasing to be achieved over the 332-515 nm spectral range with the excimer laser pump radiation. The value of the conversion efficiency ~o for the maximum oscillator power at the wavelength Xma x ranged from 1.7-10.8%, depending onthe type of dye. The relatively low value of the conversion efficiency for laser radiation in the oscillator is associated with the large losses necessary when using a highly selective laser resonator. A high conversion efficiency for pump radiation is observed with coumarin dyes, which is associated with a higher quantum yield for fluorescence in these compounds and with a high absorption value at the pump wavelength (308 nm). The second part of the study investigated the feasibility of increasing the pump radiation conversion efficiency achieved in the oscillator. Under the given conditions of radiation monochromaticity, traditional method for solving this problem is to use an amplifier. To this end, an amplifier stage was included in the laser design, consisting of a 40 mm long flow-through cuvette and a pump path with 3 nsec optical delay line. The cuvette

Wide continuous wavelength tuning of a narrow linewidth DBR laser

A continuous wavelength tuning range of 5.4 nm is obtained for a three-section DBR (distributed Bragg reflector) laser by applying one control current in both forward and reverse bias directions. In the reverse direction no significant linewidth broadening is seen due to the absence of injection-recombination shot noise, and a linewidth of less than 3 MHz is obtained over a wavelength span of 1.8 nm. The minimum linewidth observed is 580 kHZ. >

Broadband tunable single frequency diode-pumped erbium doped fibre laser

A single frequency erbium fibre laser with continuous wavelength tuning over the range 1525–1568 nm has been demonstrated using a unidirectional loop mirror (ULM) configuration. The fibre laser is diode pumped at 1480 nm with a threshold of 9mW, slope efficiency of 12% and has a linewidth of less than 295 kHz.

Continuous wavelength tuning of two-electrode vertical cavity surface emitting lasers

The first continuously wavelength-tunable vertical cavity surface emitting laser is reported. The total tuning range is 18 AA (540 GHz) including a 4-6 AA blue shift. The laser power remains nearly constant with the tuning current for most of the tuning range. No mode hopping was observed. Using time-resolved spectrum measurement, the tuning time is determined to be approximately 300-400 ns.

Continuous wavelength tuning of Brewster angled semiconductor lasers

A Brewster angled InGaAsP/InP semiconductor laser coupled to an external two grating cavity has been tuned continuously over 55 nm spectral range. This was made possible by making high spectral selectivity of the external feedback.

A full-automaic tunable dye-laser system with a rapid dye-exchanger.

A microcomputer controlled dye laser system pumped by a TEA nitrogen laser is developed as a tunable light source with a wide spectral range for analytical atomic spectrometory in industry. A turret exchanger containing 13 dye-cells inside makes a rapid dye exchange possible by the aid of a computer controlled tuning device. The tunable range is from 360 nm to 740 nm, and the continuous wavelength tuning over the whole spectrum is demonstrated with a rapid access time.

Widely tunable narrow linewidth erbium doped fibre ring laser

An erbium doped fibre ring laser enabling singlemode operation over a continuous wavelength tuning range of 44 nm (1528nm–1572nm) with laser linewidths of less than 10kHz is reported.

Over 7nm (875GHz) continuous wavelength tuning by tunable twin-guide (TTG) laser diode

The recently developed tunable twin-guide (TTG) laser, which needs only a single control current for continuous wavelength tuning, was fabricated according to an optimised design. Continuous tuning ranges of 7-1 nm (890 GHz) under constant laser current and 5-4 nm (675 GHz) at a constant light output power of 1 mW were achieved at 25 o C

Acoustooptic tunable filters in narrowband WDM networks: system issues and network applications

The system issues and network applications of acoustooptic tunable filters (AOTFs) are discussed. AOTFs are thought to be attractive system components in dense wavelength-division multiplexed (WDM) networks because of their broad continuous electronic wavelength tunability and narrow filter bandwidth. Their unique multiwavelength filtering capability adds a greater dimension of flexibility to network design. The characteristics of the AOTF are reviewed from a system viewpoint and the performance and capabilities of bulk-devices, integrated-optic devices, and fiber-based devices are discussed and compared. Three network applications using the acoustooptic tunable filters are described. The first application is as wavelength-tunable receivers or taps for local users in a subscriber loop distribution network. The second is as multiwavelength tunable receivers in a broadcast local-area cross-connect for packet communication with very-high-throughput data rate. The third is as wavelength-selective space-division switch fabric for routing and cross-connect between central offices. Future prospects and various issues for future research are also discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A continuously tunable GaAs diode laser with an external resonator

Design and characteristics of an “external cavity single mode GaAs diode laser” are described which allow continuous wavelength tuning over 50 GHz without mode hops. Tuning is achieved by synchronous tilting of both a thin solid etalon and a Brewster plate inside the laser resonator. Stabilizing the laser frequency to an external Fabry-Perot interferometer yields a frequency stability of ≦1 MHz at output powers up to 20 m W.

Performance characteristics of an injection-controlled electron-beam pumped XeF(C to A) laser system

Characteristics of an injection-controlled electron-beam pumped XeF(C to A) laser are investigated with emphasis on efficient wideband tuning and scaling issues. Using a quasi-CW dye laser as an injection source, data are obtained that describe the laser characteristics over a wide parameter range. A high-Z electron-beam backscattering reflector inside the laser reaction cell improved the electron-beam energy deposition by 40%, resulting in an increase of the amplified laser output by more than a factor of four. Efficient and continuous wavelength tuning between 470 and 500 nm is achieved with an output energy density of approximately 1 J/l, and an intrinsic efficiency of approximately 1% throughout the entire tuning region. >

Spectral characteristics for 1.5 µm DBR laser with frequency-tuning region

A 1.5 μm frequency-tunable distributed Bragg reflector (DBR) laser was developed. Frequency tuning was performed by injecting current into the DBR region where the refractive index was reduced to result in the Bragg frequency change. Threshold current and external quantum efficiency were 16 mA and 26 percent, respectively. The maximum continuous wavelength tuning range was 1.03 nm ( = 136 GHz). Spectral linewidth was maintained at an almost constant value when the wavelength was tuned. Large frequency modulation (FM) efficiency of 1-3 GHz/mA and flat FM response up to a few hundred MHz were obtained.

Flashlamp-pumped Cr&amp;lt;sup&amp;gt;3+&amp;lt;/sup&amp;gt;:GSAG laser

Flashlamp-pumped vibronic lasing has been demonstrated at room temperature with the garnet Cr3+: GSAG. Continuous wavelength tuning was observed from 765 to 801 nm in preliminary experiments. An energy output of 110 mJ/pulse was obtained at 784 nm with a slope efficiency of 0.12 percent. Wavelength dependent gain and loss data are presented and are discussed with reference to Cr3+: GSGG measurements.

The Los Alamos free electron laser oscillator: Optical performance

During nearly a year of oscillator experiments, the Los Alamos free electron laser has demonstrated high-power and diffraction-limited output capabilities with continuous wavelength tunability in the infrared. A conventional L-hand rf linear accelerator produced a 100-μs-long, 2000-pulse train of 35-ps-wide electron-beam pulses with peak currents to 50 A and nominal energy of 20 MeV. Small-signal gain in excess of 40% was generated in a 1-m, plane-polarized, uniform-period undulator for wavelengths between 9 and 11 μm. Best performance included an electron-energy extraction efficiency of ∼1%, 10-MW peak output power, and a corresponding average power of 6 kW over a 90-μs pulse train. A Strehl ratio of 0.9 characterized the output spatial beam quality.

Use of a photoprotolytic reaction for extending the tuning range of the emission wavelength of a 3-methoxybenzanthrone laser

An investigation was made of the luminescence and lasing characteristics of 3-methoxybenzanthrone solutions of different acidity. It was established that at a certain acidity of a solution the transfer of molecules of this dye to an excited state produced a new ionic form resulting from the attachment of a hydrogen ion. When a solution with the optimal acidity was pumped with the second harmonic of a ruby laser, stimulated emission was observed for both ionic forms and continuous wavelength tuning was attained in the range 540–660 nm.

Wavelength tuning of nitrogen pumped dye laser

In this paper a method is described for continuous wavelength tuning of nitrogen pumped dye laser by changing the concentration of an additional dye in the lasing solution.

Four-wave sum mixing (130–180 nm) in molecular vapors

It is demonstrated that molecular vapors such as nitric oxide, bromine, and benzene can be used for resonantly enhanced four-wave mixing into the vacuum ultraviolet. Coherent radiation in the 130–152-nm region has been generated in nitric oxide, and continuous wavelength tunability achieved by pressure broadening the rotational structure at 10 atm. Estimates of the third-order nonlinear susceptibility are shown to be consistent with the observed conversion efficiency in nitric oxide.

Uv Dye Lasers

Abstract The moat important property of visible dye lasere, that is continuous wave length tuning, stimulated the search for dyes capable to lase UV. And they were founed in 16681. Now the need In tunable UV laeers for applications in spectroacopy, photochemistry, isotope separation, remote air and sea probing, etc. ie only more clearly Been. The object of thie paper is to review shortly some recent advances In UV dye lasers.

Wavelength tuning of an intracavity pumped CW mode-locked dye laser

Continuous wavelength tuning for DTDC in ethylene glycol intracavity pumped by mode-locked 632.8 nm pulses was found for equalized round trip delay when the dye laser cavity was made slightly longer than the pump laser cavity. For equal cavity lenghts the dye laser oscillates in narrow band lines in the vicinity of Ne transitions.