High-peak-power picosecond optical pulse generation from highly RF-modulated InGaAsP DH diode laser

The feasibility for generating high-peak-power ultrashort optical pulses was demonstrated from a highly RF-modulated InGaAsP DC-PBH laser diode at 1.3 ?m for the first time. Measured pulse width is found to be approximately 28 ps at 7 mW averaged output power, and peak output power reached about 1.2 W at 210 MHz repetition frequency. Higher peak output and shorter optical pulses could be expected with this type of semiconductor diode laser in the near-infra-red region.     

Self-Q-switched picosecond optical pulse generation with tandem-type AlGaAs TJS laser

Experimental results are presented for ultrashort optical pulse generation by an AlGaAs tandem-type laser with transverse junction stripe structure. The shortest optical pulse width of 14 ps was observed by an ultrafast streak camera, while typical pulse widths were about 20 ps. Further shorter pulses may be expected with this type of semiconductor laser by adequate control of the saturable absorber region.     

Longitudinal mode competition in a pulse modulated AlGaAs DH semiconductor laser

Mode competition in pulsed AlGaAs lasers, which oscillate in a few longitudinal modes, is studied by time resolved spectrum measurement. Only a single mode oscillates at a time; other modes are suppressed. Mode transition time is 30 ns which coincides with theoretical evaluation.     

Transform-limited picosecond optical pulses from a mode-lockedInGaAs/AlGaAs QW laser with integrated passive waveguide cavity and QWmodulator

Using a novel single-top molecular beam epitaxy growth technology on nonplanar substrates, an InGaAs/AlGaAs laser amplifier has been integrated with a 4-mm-long passive waveguide cavity and a QW modulator. Lasing action of the entire structure was achieved by a current of 60 mA flowing through the amplifier section. Mode-locking experiments in which an RF signal was applied to the modulator segment led to nearly-transform-limited pulses with a duration of 4.4 ps and a time-bandwidth product of 0.43     

Characteristics of RF injection locking of self-pulsing in an AlGaAs DH junction laser

The minimum RF power required for injection locking of the light pulsations in the output of a CW room-temperature AlGaAs double-heterostructure (DH) junction laser was found to depend exponentially on (f-f_{r}), wherefis the RF injection frequency and fris the self-pulsing frequency, and also, to depend inversely on the self-pulsing strength of the laser. Nearly 100-percent modulation depth is achievable atf=f_{r}, and slight reduction of modulation depth occurs whenf gg f_{r}.     

用皮秒激光产生宽度可调的高压电脉冲

本文报道用两个具有可变相对延时的皮秒激光脉冲,先后驱动两个光电子开关,产生前后沿均为亚毫微秒的宽度可调高压电脉冲。     

Generation and optimum control of picosecond optical pulses fromgain-switched semiconductor lasers

The generation of picosecond pulses from gain-switched semiconductor laser diodes is studied. Theoretically, common-rate equations are used to give pulse width and amplitude as a function of external parameters. The numerical predictions are compared with experimental results. It is found that optimum conditions can be achieved by an appropriate choice of the bias current     

Generation of 10 nJ picosecond pulses from a modelocked fibre laser

Wavelength-tunable very high power soliton fibre lasers are constructed using chirped fibre Bragg gratings. Near-bandwidth limited pulses with widths of 4.0 ps and pulse energies up to 10 nJ are generated directly from passively modelocked erbium fibre lasers. A stable pulse repetition rate of 17 MHz is obtained, giving rise to an average modelocked output power of 170 mW     

Generation and kilohertz rate amplification of synchronizedfemtosecond and picosecond laser pulses

Synchronized femtosecond and tunable picosecond laser pulses have been generated using a linear cavity configuration in both lasers. The long-term stability of the synchronization, as well as the frequency of the synchronously pumped femtosecond dye laser, is assured by active stabilization of the cavity length. Additionally, the picosecond and femtosecond pulses have been amplified in dual amplifier chains to pulse energies in the microjoule range at a 1 kHz repetition rate. The total peak intensity available for two-photon, nonlinear excitations is on the order of 10⁹ times greater than that available from unamplified beams     

同步泵浦染料激光器产生高功率可调谐微微秒激光脉冲

本文介绍一种用Nd:YAG双锁模的倍频脉冲序列,同步泵浦以曲率半径R=2m的凹面光栅所组成的染料激光器,实现了高功率可调谐的微微秒染料激光输出。用条纹照相机对同步泵浦锁模激光系统中各部分的输出特性进行了实验研究和测试。     

Generation and wavelength switching of picosecond pulses by optically modulating a semiconductor optical amplifier in a fiber laser with optical delay line

A novel actively mode-locked fiber laser having a semiconductor optical amplifier playing the roles of both a gain element and an optically controlled mode-locker and eight cascaded fiber Bragg gratings playing the role of the wavelength selecting element is proposed and demonstrated. Stable amplitude equalized pulse trains with a pulsewidth about 43 ps at 2.5 GHz have been obtained by injecting optical control signals into the laser. Wavelength switching among eight wavelengths is achieved by merely tuning an intracavity optical delay line. This all-optical generation and wavelength-switching scheme should be useful in applications where picosecond pulse trains at high repetition rates are desired.     

Bandwidth limited picosecond optical pulse generation from actively mode-locked AlGaAs diode laser

A simple configuration made of a conventional AlGaAs diode laser without antireflection coating combined with an external reflector and an optical etalon was proved to be practically feasible to generate bandwidth limited mode-locked optical pulses of 30 ps duration by synchronous modulation at the external cavity mode interval. Generated optical pulse shape was found to be Lorentzian rather than Gaussian for the first time, based on the measurements of both the s.h.g. correlation method and the ultrafast streak camera.     

Modulation frequency characteristics of directly optical frequency modulated AlGaAs semiconductor laser

Optical frequency spectra of directly frequency modulated AlGaAs semiconductor laser in the 0?5.2 GHz range were measured by using a Fabry-Perot interferometer and a birefringent optical filter. The frequency deviation is linearly proportional to the RF modulation current. The measured modulation frequency characteristics for the frequency deviation show that the thermal effect is predominant in the frequency below 10 MHz. It has a resonance peak which behaves just like the peak observed in the modulation. Experimental results agreed well with theoretical values calculated by considering thermal effect and carrier-dependent refractive index variation.     

激光等离子体诊断用微微秒紫外高功率激光脉冲的产生

氙灯泵浦的可调谐染料激光器锁模脉冲用XeCl准分子激光器泵浦的三级染料激光放大器放大后,经倍频再用XeCl准分子激光器放大,在308毫微米处获得了微微秒高功率激光脉冲输出,其峰值功率可达500兆瓦,功率净增益为200。     

Filtering directly modulated laser diode pulses with a Mach-Zehnder optical delay interferometer

An improvement in the waveform of 10 Gbit/s pulses from a directly modulated DFB laser by the use of an optical delay interferometer (ODI) is demonstrated. The insertion of this device in the transmitter suppresses amplitude overshoot and enhances the extinction ratio by 2.7 dB. It is shown that the transmission distance is increased by the addition of the ODI.     

Second-harmonic generation by picosecond optical pulses

The generation of second-harmonic radiation in a non-linear dielectric by an arbitrary broad-band optical signal is analyzed and application of the theory is made to harmonic generation by a short pulse. The spectrum and time dependence of the harmonic radiation is calculated in terms of the corresponding quantities for the fundamental pulse. Several types of pulses, including a frequency-swept pulse, are treated. Experimental results on the second-harmonic spectrum are presented and compared with the theory, as are previously reported results on the time dependence.     

Generation of frequency-chirped optical pulses in a large-slippagefree-electron laser

We have investigated the optical output of the free-electron laser for infrared experiments (FELIX) when it is driven by an electron beam with a ramped energy. We show that the applied slow ramp on the electron beam energy leads to a frequency chirp on each picosecond optical pulse. Typical values for the chirp are 0.2% frequency sweep across a 1.5-ps-long optical pulse. The optical pulses were analyzed with a double-grating pair and with a second-order autocorrelator. The pulse duration was reduced in the double-grating pair by 20%. A linear dependence of the chirp on the cavity desynchronization was measured     

Tunable dual-wavelength picosecond optical pulses generated from aself-injection seeded gain-switched laser diode

A novel scheme to generate dual-wavelength picosecond optical pulses has been demonstrated. The pulses are obtained by self-injection seeding of a gain-switched laser diode simultaneously at two different wavelengths. Optical feedback is provided by a partially reflecting fiber mirror. Single-mode pulses at alternate wavelengths around 1.3 μm have been generated. The pulse width varies from about 40 to 50 ps. The output wavelengths can be tuned by changing the electrical modulation frequency. Spacing between the wavelengths can also be controlled by adjusting the length of the dispersive fiber cavity. Our experimental data are in good agreement with the calculated results     

CW autocorrelation measurements of picosecond laser pulses

Completely general and novel expressions are presented fornth-order fast or slow correlation functions, with or without background contributions, from which more specializednth- and second-order auto-correlation functions are derived. A straightforward method for obtaining CW autocorrelation measurements of picosecond pulses is then described which employs an audio loudspeaker driven at 30 Hz in one arm of the correlator to permit autocorrelation display at this frequency. Results of the application of this device to measurements of the picosecond pulses from a CW synchronously mode-locked Rhodamine 6G dye laser are presented.