Generation Of Tunable Picosecond Pulses Research Articles

Electronically tunable picosecond pulse generation from Ho3+-doped fluoride fiber laser using frequency-shifted feedback.

In this Letter, we demonstrate electronically tunable picosecond (ps) pulse emission from the 5I6-5I7 transition of the Ho3+ ion by using an acousto-optic tunable filter. The holmium- and praseodymium-codoped ZBLAN fiber laser produced sub-50 ps pulses over a 100 nm tuning range, critically reaching a longest wavelength of 2.94 µm, which overlaps with the peak absorption of liquid water. Measured pulse energies of 8.1 nJ well exceed those expected from picosecond solitonic operation, suggesting possible application in ablative medicine. Furthermore, we present harmonically mode-locked operation of the oscillator, which indicates the possibility of expanding the capabilities of mid-infrared frequency shifted-feedback lasers through the ability to achieve higher pulse repetition rates.

Diode-pumped femtosecond Tm3+-doped LuScO3 laser near 2.1 μm.

We report on the first demonstration, to the best of our knowledge, of a diode-pumped Tm:LuScO3 laser. Efficient and broadly tunable continuous wave operation in the 1973-2141nm region and femtosecond mode-locking through the use of an ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror are realized. When mode-locked, near-transform-limited pulses as short as 170fs were generated at 2093nm with an average output power of 113mW and a pulse repetition frequency of 115.2MHz. Tunable picosecond pulse generation was demonstrated in the 2074-2104nm spectral range.

Generation of tunable picosecond pulses by pulse stacking in an Yb-fiber gain-assisted pulse stacker

We report on the generation of tunable picosecond pulses of high repetition rate by pulse stacking in an Yb-fiber stacker that benefited from high optical gain, properly time delay and laser synchronization. The gain-assisted pulse stacker could be controlled for pulse shaping to produce tunable pulse duration from ps to sub-ns range by managing the intracavity dispersion and adjusting the time delay. The energy loss during the pulse shaping process was compensated by the gain of a 60-cm-long Yb-fiber pumped by a diode laser. The temporal profiles of the output pulses were measured by using a special cross-correlation technique. The duration of the stacked pulses could be tuned from 5 to 200 ps with a controllable time interval.

Analysis of tunable picosecond pulse generation from a distributed feedback Ti:sapphire laser

A distributed feedback Ti:sapphire laser (DFTL) pumped by a 532nm Q-switched pulse is proposed for the generation of tunable picosecond pulses. With coupled rate equation model, the temporal characteristics of DFTL are obtained. The numerical solutions show that the DFTL pulse with a 50-ps pulse duration and as much as 3.5mJ pulse energy can be obtained under 40-mJ, 5-ns pulse pumping. The dependence of output pulse width on the laser crystal's length, pumping pulse duration and pumping rate is also discussed in detail.

Simple approach for wavelength tunable picosecond pulse generation by an external injection seeding scheme

A simple scheme to generate wavelength tunable picosecond pulses by the external injection seeding of a gain-switched Fabry-Perot laser diode (FP-LD) is demonstrated. The key parts of the system consist of a FP-LD, a fiber Bragg grating (FBG), and a 3-dB coupler. The peak wavelength can be tuned from one longitudinal lasing mode to another by changing the Bragg wavelength of the FBG. The wavelength tuning range achieved is about 10 nm and the overall side mode suppression ratio (SMSR) is better than 15 dB.

Monolithic multisegment mode-locked DBR laser for wavelength tunable picosecond pulse generation

Monolithic active/passive mode-locked DBR laser for 4/spl times/10 Gb/s optical time division multiplexing (OTDM) application at 1.55 /spl mu/m are realized by low-cost 2"-technology. The devices show excellent performance at STM-64 frequency: they deliver nearly time-bandwidth limited (<0.4) and wavelength tunable (4.3-nm range) optical return-to-zero (RZ) pulses of down to 8-ps pulsewidth.

Generation of tunable picosecond pulses by synchronous pumping of a periodically poled lithium niobate optical parametric oscillator

A tunable quasi phase-matched optical parametric oscillator synchronously pumped at 1.047 µm is reported. The signal was tuned from 1.33 to 1.45 µm, corresponding to a calculated idler tuning range of 2.67 – 4.86 µm. Average signal powers of up to 100 mW and pulse durations of 3.2 ps were obtained.

Highly efficient generation of tunable picosecond pulses in an LiF:F2- laser crystal

An investigation was made of a synchronously pumped pulsed LiF:F2- crystal laser. The pump radiation was provided by a neodymium phosphate glass laser operating under passive mode-locking conditions and generating pulses of 7 ps duration. The LiF:F2- laser generated 2 ps pulses tunable in the 1.10–1.22 μm range and the efficiency of the conversion process was 35%. Under the conditions of quasi-cw nanosecond pumping and active mode locking the LiF:F2- laser generated pulses of duration of the order of 400 ps.

A time-compensated spectral filter for transform-limited tunable picosecond pulse generation from spectro-temporal-selection dye lasers

Diffraction and transform-limited picosecond tunable pulses are generated from Spectro-temporal-Selection (STS) dye lasers by using a new extra-cavity filter. This filter is based on a grazing-incident grating and arranged in the configuration of a folded dispersive delay line. Thus, it provides both high spectral selectivity and controllable temporal compensation for elimination of pulse broadening. Direct production of diffraction- and transform-limited picosecond dye laser (10 µJ, 50 ps) pulses spectrally adjustable between 398 and 702 nm is demonstrated in a compact device, with 8 ns pump pulses from a nanosecond nitrogen laser.

Picosecond infrared optical parametric generation in KTP using a diode-laser-pumped solid-state laser

We report the generation of tunable picosecond pulses in the near infrared by synchronous pumping of an optical parametric oscillator based on the crystal KTP with a frequency-doubled, actively mode-locked, Q-switched, diode-laser-pumped Nd:YLF laser at 523.5 nm. The oscillator provides tunable radiation over the ranges of 0.946-1.020 microm and 1.075-1.172 microm in pulses of ~8-ps duration, with average output powers approaching 2 mW, at a 500-Hz repetition rate. The threshold Q-switched pulse energy was 4 microJ, and pump depletions as high as 56% were observed when pumping 5.5 times above threshold. At this pumping intensity the amplitude stability of the optical parametric oscillator output pulses was +/-2%.

Experimental and theoretical investigation of tunable picosecond pulse generation in longitudinally pumped dye laser generators and amplifiers

Picosecond pulse generation in longitudinally pumped dye laser generators and amplifiers is studied experimentally and theoretically. Frequency-tunable pulses between 720 and 940 nm are generated with a picosecond ruby laser pump source. The amplification of spontaneous emission and of seeding pulses in the generator and amplifier cells is investigated. Stimulated emission cross-sections and excited-state absorption cross-sections are determined by computer simulations. The coherence properties of the generated radiation are analysed. Resonance Raman contributions are resolved.

Generation of tunable picosecond pulses between 1.18 μm and 1.53 μm in a ring laser configuration using dye No. 5

Abstract Extended tunability of picosecond dye laser pulses between 1.18 μm and 1.53 μm is achieved with switching dye no. 5 in a synchronously pumped ring laser configuration. The pulse duration amounts to 27 ps. The maximum energy conversion is 2%.

High-power TEA-TE nitrogen laser system

The authors have created, under laboratory conditions, a reliable nitron laser system generating powerful short radiation pulses with stable amplitudes (1ambda /SUB g/ = 337.1 nm), which can be used in a series of kinetic experiments. The authors are planning to use the system for generation of tunable picosecond pulses in dye solutions.

Generation of tunable picosecond pulses in a simple distributed feedback dye laser under N 2-laser pumping

Simple possibility of single tunable picosecond pulse generation in a conventional inexpensive distributed feedback dye laser (DFDL) is demonstrated. It is shown that when a TEA N 2-laser is used for pumping no diffraction grating is necessary in the DFDL optical scheme for operation in the picosecond regime. Hence wide-range spectral tuning from 357 to 665 nm was easily achieved. When pumped with a 0.6 ns 40 kW pulse of the TEA N 2-laser the DFDL generated pulses as short as 7 ps with time-bandwidth product better than 0.6 and peak power ∾ 10 kW. At a repetition rate of 50 pps the shot-to-shot energy stability of a single picosecond pulse was ±18% at ±7% stability of the TEA N 2-laser.

Generation of tunable picosecond pulses in the medium infrared by down-conversion in AgGaS 2

Picosecond pulses from a mode-locked Nd:YAG laser and a traveling-wave dye laser are mixed in an AgGaS 2 crystal to generate pulses at the difference frequency. The dye laser is tunable between 1200 nm and 1460 nm resulting in a tuning range of the parametric pulses from 3.9 μm to 9.4 μm. The spectral bandwidth is quite narrow. A value of Δṽ=6.5 cm -1 was measured which is constant over the whole tuning range. Several percent of the Nd:YAG laser photons are converted to infrared photons. Pump pulses of 21 ps give parametric pulses of 8 ps.

Generation of tunable picosecond pulses in the vibrational infrared by stimulated electronic Raman scattering of rhodamine-dye-laser pulses from the 6s–5d cesium transition

The first reported use of a rhodamine-dye laser to generate tunable high-power picosecond pulses in the vibrational infrared is described. By using stimulated electronic Raman scattering from the 6s-5d transition in a superheated cesium vapor, we have shifted I-psec pulses from an amplified rhodamine-dye laser (568-590nm) to 3040-2320 cm(-1) (3.3-4.3 microm). Somewhat longer pulses have been shifted to 1950 cm(-1) (5.1 microm). Peak infrared energies of 11 microJ, representing a quantum efficiency of 4.6%, were obtained at a 10-Hz repetition rate. Tuning to longer wavelengths with short pulses is limited by nonlinear processes but should be possible by further reductions of cesium dimer effects.

Parametric generation of tunable picosecond pulses in proustite between 1.2 and 8 μm

Infrared pulses were generated over a wide tuning range in a single-path system consisting of Nd:YAG laser pulses and two proustite crystals. A bandwidth of approximately 10 cm -1 for idler pulses was observed. The energy conversion efficiencies varied strongly with frequency between 10 -2 and 10 -4. Bulk damage did not occur for pump intensities up to 6 GW/cm 2.

Dye lasers with optically induced distributed feedback

Results are presented of experimental investigations of the characteristics of radiation from a dye laser with an optically induced distributed feedback (DFB) in solid matrices. It is shown that DFB lasers can be used effectively to extend the tuning range of the lasing wavelength into the ultraviolet and infrared. Efficient generation of tunable picosecond pulses in DFB lasers is reported and a new type of DFB laser is described, comprising holographic DFB dye lasers which can emit a narrow radiation line for a pump spectrum of arbitrary width.

Generation of tunable picosecond pulses in the ultraviolet and blue-green parts of the spectrum with the aid of a distributed-feedback dye laser

An experimental investigation was made of the conversion of the radiation of a distributed-feedback dye laser to the ultraviolet and blue-green parts of the spectrum by the methods of frequency doubling and mixing, resulting in generation of picosecond pulses. The shortest wavelength emitted so far from distributed-feedback dye lasers was 272 nm.

Tunable picosecond pulse generation from the passively mode-locked coumarin 6 dye laser

Using the saturable absorber 2-(p-Dimethylaminostyryl)-benzothiazolylethyl iodide, coumarin 6 has been passively mode-locked for the first time to give fully modulated trains of pulses of ∼4 ps duration and with peak powers of ∼3 MW tunable over the spectral range 526–547 nm.