We report on the generation of short optical pulses by utilizing the non-linear absorption characteristics of a multiple quantum well (MQW) electro-absorption modulator, which is monolithically integrated with a MQW wavelength-tunable distributed Bragg reflector (DBR) laser on a single chip. Optical pulses as short as 39 ps and 15 ps have been generated at a repetition rate of 3 GHz and 10 GHz, respectively, with a broad tuning range of 5.4 nm near 1554 nm lasing wavelength.

Compact and efficient sources of high power ultrafast optical pulses are needed to incorporate high speed optical information processing techniques into future photonic networks. In this paper, the robust timing stability associated with optical mode-locked pulse trains from semiconductor diode lasers is examined as an alternative to standard methods of providing synchronous timing signals in future photonic networks. Here, it is demonstrated how these sources may play a role in several photonic network scenarios, such as optical clock distribution, photonic network synchronization, and all optical clock recovery.

Short infrared pulses have been generated by nonlinear mixing of the wavelengths from a two color femtosecond modelocked Ti:Sapphire laser. The pulses can be tuned from 7 to 12 micrometers and are used to perform a direct measurement of the speed of a GaAs/Al_0.2Ga_0.8As quantum well infrared photodetector. The electrical response of the detector has rise and decay times of less than 95 ps and the FWHM is 115 ps.

We have designed and demonstrated two wide bandwidth passive frequency doublers capable of second harmonic generation over the entire 100 nm cavity optics bandwidth of a passively modelocked Ti:Al₂O₃ laser with minimal loss in conversion efficiency. In addition, we demonstrate that focussing effects are extremely important in determining the bandwidth in sum frequency mixing of ultrashort pulses in the near VUV region. This effect is demonstrated with noncollinear sum frequency mixing performed between the fundamental and the third harmonic subpicosecond pulses of this laser source.

Two collinear and synchronous modelocked pulse trains, with central wavelength separation adjustable between 55 and 90 nm, were obtained from a single cavity modelocked Ti:sapphire laser. Near transform limited pulses of duration 50 to 70 fs were generated at each wavelength, with very small jitter between the two color pulses.

We report on the generation of high-power, high-repetition-rate femtosecond pulses tunable in the visible by intracavity frequency-doubling of a KTiOPO₄ (KTP) femtosecond optical parametric oscillator (OPO). The KTP OPO is synchronously pumped by a self-modelocked Ti:sapphire laser producing pulses of 225 kW peak power at a repetition rate of 81 MHz (115 fs pulsewidth), and a center wavelength of 790 nm. Using a 1.5 mm thick KTP gain crystal and a 50 micrometers (beta) -BaB₂O₄ frequency-doubling crystal, we achieve up to 240 mW of sub-100 femtosecond pulses tunable in the range of 580 to 660 nm. The potential tuning range of the frequency-doubled KTP OPO, when pumped at 790 nm, is approximately 500 to 750 nm.

Compact all-solid state laser sources are developed for femtosecond pulse generation tunable around 193 nm utilizing high peak power Ti:sapphire oscillator/amplifier systems and phase matched sequential sum frequency conversion in three (beta) -barium-borate (BBO) crystals arranged in different schemes. Using thin crystals and a delay line for optimization of the temporal overlap of the interacting pulses in the last conversion stage 190 fs optical pulses with pulse energies of more than 2 (mu) J at 193 nm at 20 Hz repetition rate and 170 fs pulses with pulse energies of up to 4 (mu) J at 200 nm (0.8 (mu) J at 193 nm) for 1 kHz repetition rate are produced with excellent spectral, temporal, and spatial stability.

The recent development of femtosecond optical parametric oscillators has extended the wavelength range over which ultrafast lasers are available (visible to 3.5 micrometers has been demonstrated). The options in cavity configurations, phase matching, and nonlinear optical crystals used with a Ti:sapphire pump laser are discussed. Results of an OPO using the nonlinear crystal KTiOAs₄, which is potentially tunable to 5 micrometers , are presented.

We studied the use of a highly nonlinear self-focusing element made of ZnS in an all solid- state self-starting Kerr lens modelocked Ti:sapphire laser. The results of our calculations show that the relationship between cavity losses and instantaneous intracavity power in such a laser is quite different than previously reported. The use of ZnS eliminates the need for saturable dyes or cavity modulation to initiate self-modelocked operation. We show experimentally that the pump power threshold for self-modelocking of a Ti:sapphire KLM laser can be significantly reduced by the use of a highly nonlinear intracavity element made of ZnS. Modelocking in the laser tested, which produced pulses with duration adjustable from 5 ps to 50 fs, was self-starting by Kerr lens mechanism alone. Because of the broad nonlinear response of ZnS the method is wavelength insensitive unlike quantum well saturable absorber/mirror designs.

The starting mechanism in coupled-cavity, additive pulse mode-locked (APM) lasers is discussed theoretically and demonstrated experimentally. Short- and strong-mode beating noise bursts that can overcome dynamic gain saturation in large emission cross-section gain media result from the etalon effect of the coupled cavity that forces lasing at two separate frequencies. We have measured terahertz-mode beating fluctuations, that are in quantitative agreement with our theory, in a coupled-cavity NaCl color-center laser. A detailed comparison between theory and experiments is presented, and implications regarding other laser systems are discussed.

We have constructed a self-starting Kerr-lens mode-locked Ti:sapphire laser pumped synchronously by a mode-locked, LBO-doubled Nd:YAG laser. Using a home-built beam- pointing stabilizer, beam wander of the 532 nm pump is reduced by a factor of 25, thus enabling long term operation of TEM₀₀ nearly transform limited pulses with amplitude, repetition rate, and pulsewidth fluctuations comparable to or better than those of Ar-pumped Ti³⁺:Al₂O₃ lasers. Interferometric autocorrelation using second harmonic in reflection from GaAs yielded a pulse width of 30 fs, limited by the dispersion of wide bandwidth cavity optics that permit tunability from 0.7 to 1.0 micrometers .

We demonstrate mode-locked two-wavelength synchronized operation of a single, cw pumped Ti:Sapphire laser. There is no active feedback or external cavity. The measured cross correlation is 105 fs. Wavelengths as much as 57 nm apart can be simultaneously cross-mode- locked. We then investigate the nonlinear interactions between the pulses. We show the nonlinear interaction caused by self focusing can correct for a difference in cavity lengths of up to +/- 3 micrometers corresponding to 20% of the pulse width on each round trip. Further, we show that the concept of mean group delay can be extended to a pair of pulses with disparate spectra and spatial distribution in a nonlinear regenerative system.

In this paper, a new ultrashort pulse lasers model has been established, which includes the nonlinear effects. A quantum mode-locked equation has been derived using the Hamiltonian function for the system of lasers on the basis of the model. The solutions for pulse field and photon distribution are obtained. We have examined the dependence of the pulse energy, width, and chirp on the laser parameters in steady state, after replacing the envelope operator by the envelope of the pulse in the equation. For the first time, we have discovered the self- steady characteristic of the ultrashort pulse lasers, and some methods that can be used to reduce the pulse width and improve the stability of the lasers are given.

With intracavity dispersion compensation for self-mode-locked or active mode-locking Ti:sapphire lasers, pulses as short as 56 fs can be directly produced. Using the results of recent experimental research, we present a theoretical analysis of solid-state Ti:sapphire femtosecond lasers. In our studies on the dynamics of self-mode-locked Ti:sapphire femtosecond lasers we used the analysis method of quantum theory. We have established a quantum mode-locked equation which describes the pulse shaping mechanism of Ti:sapphire lasers. Number density and the average value of the pulse field are obtained in a Schrodinger picture. After transforming the quantum mode-locked equation into a classical equation, we analyzed the gain medium characteristic, and we found that the curve of the net gain for the Ti:sapphire must have a hollow close to the output frequency. Furthermore, the pulse shaping mechanism has been examined.

While the gain bandwidth of Er-doped fiber amplifiers is in the range of 60 fs, most fiber figure eight lasers produce approximately 200 fs pulses. We show that higher order terms, including third-order dispersion, self-frequency shifting, and self-steepening, severely limit the efficiency and pulse quality for ultra-short pulses propagating in the nonlinear amplifying loop mirror, which acts as a gain medium and a modelocker in these lasers. We also compare the nonlinear optical loop mirror used as an ultra-fast all-optical switch at various control pulse power levels.

It is well known that Neodymium glasses are widely used as active media in powerful picosecond laser systems. However, low thermal conductivity of glasses with broad bands of absorption and luminescence limits their use in pulsed lasers with high repetition rate. At the same time, disordered crystals having broad inhomogeneous bands of active ions and combining properties of both glasses and crystals may be reckoned as active media for ultrashort pulse lasers with high repetition rate. It has been shown recently that Calcium-Niobium-Gallium disordered garnet crystals doped with Nd3+ ions (CNGG:Nd3+) with broad inhomogeneous spectrum of amplification are prospective active media for the laser generation of powerful ultrashort pulses1 . In ref. 1 a passively mode-locked (PML) with a saturable dye absorber CNGG:Nd3+ laser generated trains of 7 ps pulses at a repetition rate of 0.3 Hz. To eliminate a liquid absorber and get an all solid state laser configuration one can mode-lock a laser actively with a crystalline modulator. But while the active mode-locking (AHL) technique may lead to the generation of high stable and reproducible laser pulses with a high repetition rate, its main drawback in comparison with the PML is relatively large pulse duration, in particular, at lamp pumping. Nevertheless, the use of a highly efficient LiNb03 acousto-optic modulator (AOMJ 2 •3 in a glass laser has led to the generation of pulses with duration of 13 ps 4 , so the operation of a laser on disordered crystals doped with Nd 3+ ions actively mode-locked with the AOM is a matter of considerable interest. It is known also that LiF crystals with F 2 color centers are successfully employed for passive Q-switching6 and the application of these crystals as passive Qswitchers to AHL lasers may give sufficient rise to pulse peak power. The aim of this work is to investigate the operation of actively mode-locked with LiNb03 AOM laser on a Calcium-Lithium-Niobium-Gallium disordered garnet crystal doped with Nd3+ ions (CLNGG:Nd3+) and a LiF:F2 passive Q-switch.

The interference fringes of the interferometric second order autocorrelation curves with a peak-to-background ratio of 8:1 are measured and analyzed. The femtosecond pulses are from a colliding pulse mode locked dye laser (CPM). The autocorrelator and datum acquisition are all controlled by an IBM PC/XT computer with the software and hardware specifically designed in this work. The experimental results demonstrate that the oscillatory frequency of the fine structure within the 8:1 curves is dominantly determined by the oscillatory frequency of the interferometric autocorrelation of the fundamental wave. The curves are well fitted with the theoretical calculation for the interferometric autocorrelation trace for a hyperbolic-secant- squared pulse. The intensity autocorrelation curves are also measured. It is found that the optical delay line must be moved above a certain high speed, otherwise it is possible to get a wrong intensity autocorrelation curve and the measurement result will include some interferometric information.

With the help of the self-consistent ABCD matrix method the fundamental TEM₀₀ mode of a four-mirror cavity with active rod and hard aperture is analyzed. Cavity parameters range with the small diffraction losses at hard aperture and the decreased diffraction losses for the increased mode intensities due to self-focusing in active medium are shown immediately for practical Kerr-lens mode-locked (KLM) Ti:sapphire lasers. To do this we have obtained the generalized solution of the wave propagation equation in self-focusing medium for the arbitrary curvature radius of phase front of incident Gaussian beam. The fluctuation model of self-mode-locked lasers is used to demonstrate the generation of a stable ultra-short pulse train by the system under constant pumping for the obtained cavity parameters.

St.able pulses with a duration of 2ps derived from a special designed pulsed Nd:glass oscillator with negative feedback were amplified by the injection seeding of Q-swit.cned laser. Amplification fact.or of ~ 10• was achieved in this scheme. Chirped pulses amplification technique is used in further amplification in many staged laser system. In the works of recent. years to advance in the region of high power light. fields the Nd:glass lasers were suicessfully used and tfie highest J<OWer densities al. nearly 1020 W/cm level have been obt. ained1 • . Two problems would be solved for the beginning when such high PQwer picosecond laser system is creating.The first is the designing of J<icosecond oscillator with performed parameters. Compared witfi cw-raser system, pulsed mode-locked solia state laser offer the advantages of the increased out.put energy and short.er pulses. To overcome the shortcomings of a passive mode-locking concept the idea of feedback controllea generation was _proP.osed by many authors. N~at.ive feedback operation results in armost. 100% inode-Iocking and highly contrast. pulses at the out.put. due to controlled prolongation of the nonlinear stage of generation process. One of the main feature is that the pulse intensity in the cavity mar be maintained by negative feecffiack on the level when considerab e pulse shortening would occur. In this way, pulse duration which is close to the theoretical limit set. by the fluorescence linewidth of the laser material may be obtained. Generation of reproducible subpicosecond li~ht pulses in pulsed Nd: glass oscillator was perfectly realized in ' 4 • Second problem is concerned with the efficient preamplificat.ion of relatively weak pulse from the oscillator out.put.. One of the widely used method in preient is the ul t.rashort. pulses amplification in regenerative amplifier . However, one have to satisfy in this case to sufficiently severe reqqirement.s for the cavities length detuning Ct.o within 0.001- 0.01YJ bet.ween the oscillator and regenerative amplifier.

A first of its kind, multiterawatt, ultrashort pulse laser system is described. The system is capable of producing 125 mJ, 35 fs, 800 nm pulsed with near diffraction limited beam quality at a 10 Hz repetition rate. Methods for control of phase and amplitude distortion during sub- 100 fs amplification are presented.

Using chirped-pulse amplification in Ti:sapphire, we have generated pulses of 21 fs duration at an energy of 0.5 mJ. We have also demonstrated further amplification of chirped pulses to 45 mJ with a bandwidth capable of supporting 25 fs pulses. The amplifier design minimizes material path-length, spectral distortion and clipping, and compensates for higher-order dispersion by using a combination of prisms and diffraction gratings.

A multi-terawatt laser was used to generate and characterize plasmas appropriate for recombination pumped x-ray lasers. Thomson scattering was used to determine the electron and ion temperatures of a laser-produced, high-density helium plasma on a subpicosecond time-scale. A recombination pumped x-ray laser on the Lyman-alpha transition of hydrogen- like lithium was also studied.

The efficiency of the four-wave mixing (2 (omega) ₁ - (omega) ₂), VUV femtosecond source described by us last year (SPIE Vol. 1861) inherently relies upon a two-photon resonance enhancement occurring (in Xe gas) when (lambda) ₁ approximately equals 248.5 nm. However, it also depends upon the spatial and temporal coherence properties of the input pulses. Development of a new source for producing beams at (omega) ₁ with greatly improved coherence properties is reported here. Performance of the four-wave mixing source with these (omega) ₁ pulses is described. Femtosecond VUV pulses with energies as high as approximately 60 (mu) J are generated. As a separate topic, we propose the use of a pulsed (nanosecond) infrared laser to deplete the terminal state of an F₂ (157-nm) laser in order to greatly enhance its performance.

Frequency conversion of an ultrafast 810 nm Ti:sapphire laser has produced 15 mJ, 165-fs pulses at 405 nm with an energy conversion efficiency of 35%. Upon tripling the fundamental to 270 nm, an energy of 0.8 mJ is obtained. Unconverted 405-nm light is used to generate an ultrafast supercontinuum in water that extends from 200 nm to 600 nm. The system operates at a 5 Hz repetition rate, and is useful for applications in deep ultraviolet pump-probe ultrafast spectroscopy.

A new ultrafast photodetector with high bandwidth and high efficiency is proposed and analyzed. The new device, called optical-to-microwave transformer (OMT), consists of an input optical waveguide with periodically loaded photodiodes and a velocity-matched output microwave transmission line. Theoretical simulation shows that a bandwidth greater than 300 GHz and an external quantum efficiency of 46% can be achieved.

A unique method for determining the amplitude and phase of ultrashort optical pulses is described. The method involves differential detection of adjacent spectral components of the pulse with an ultrafast photodiode. This technique requires no optical nonlinearities, and is therefore ideal for detection of weak pulses.

The equations describing the diffraction of beams in space and the dispersion of pulses in dielectrics can be made to appear virtually identical. This suggests that a temporal equivalent to a space lens in combination with dispersion should yield a system for imaging waveforms in the time domain. This paper describes the principles of such an imaging system and suggests some applications for time scale transformation.

We formulate some general conditions concerning the applicability of linear interferometers to the measurement of the amplitude and phase of short optical pulses. In particular it is shown that any system that utilizes an integrating detector must also consist of time nonstationary filters. Two novel schemes that meet this criterion are illustrated.

The method of frequency-resolved optical gating (FROG) allows one to measure the amplitude and phase of an arbitrary femtosecond pulse on a single laser shot. An extension of this method, which we call twin recovery of excitation E-fields using FROG (TREEFROG) allows one to measure two separate laser pulses. The two dissimilar pulses are used to generate a single `TREEFROG trace' from a simple experimental apparatus, and the two pulse electric fields are determined using a modified FROG pulse-retrieval algorithm.

We describe a new design and measure data of a femtosecond streak camera with an electromagnetic focusing type streak tube. In order to reduce the temporal dispersion of photoelectrons in the streak tube, an acceleration electric field near the photocathode was achieved to 8.75 kV/mm applying a high voltage pulse to the dc biased-photocathode. We have developed a high speed deflection circuit and a Meander-type traveling wave deflector, and obtained high sweep speed of 8.76 X 10⁸ m/s on the phosphor screen. A measured data of 180 fs was obtained with 100 photoelectrons using colliding-pulse passively modelocked ring dye laser for the light source. Dynamic ranges of 10 and 20 were achieved at the temporal resolutions of 200 fs and 330 fs, respectively.

Cr³⁺:LiSrAlF₆, Cr³⁺:LiSr_0.8Ca_0.2AlF₆, and Cr³⁺:LiCaAlF₆ have been successfully mode-locked to produce a stable train of 90 fs pulses at a repetition frequency of 140 MHz. The ultrashort pulses were initiated by gently rocking the output coupler and the mode-locking was self-sustained for hours after the output coupler had remained stationary. The spectral bandwidth of the pulses was 10 nm.

Self-modelocked operation of a cw-pumped Cr:forsterite laser and the generation of pulses as short as 25 fs from a self-modelocked Cr:forsterite laser with optimized cavity dispersion are demonstrated. The pulse duration is limited by the gain bandwidth of Cr:forsterite and corresponds to only 6 optical cycles. From measurements of the performance of the laser the dispersion and nonlinearity of forsterite are obtained. Finally, a regime of modelocked operation which has not been observed previously is reported along with a tentative explanation in terms of gain saturation and gain dispersion.

Efficient modelocking of cw solid-state lasers by SHG-based modulators has been considered. A new type of modulator that utilizes an interferometrical subtraction from the generation field of its replica attenuated by second-harmonic generation (SHG) is proposed for the first time to our knowledge. Tuning parameters that control the mode-locking efficiency are the initial transmission of the modulator and transmission derivative on intensity. Self-consistent analytical solutions of an operator equation describing the laser system were obtained which satisfactorily agree with numerical simulation results based on fluctuation theory.

Ti:Sapphire (Ti:Al₂O₃) amplifier stages are typically pumped with Q-switched Nd:YAG lasers doubled to 532 nm because of good spectral overlap, short temporal width, high repetition rate (i.e., 10 Hz to > 5 kHz), and the problems associated with flashlamp pumping a material with a relatively short upper state lifetime. Limitations to this pumping method arise due to the 1 to 1.5 joule/pulse ceiling found in most commercial high rep rate Nd:YAG lasers. The availability of high quality, large aperture Ti:Sapphire rods has made the flashlamp-pumping scheme an attractive option. The front end of our laser relies on chirped pulse amplification (CPA) in laser pumped Ti:Sapphire to generate 55 mJ, 90 fsec pulses at a 10 Hz rate. We report the use of a flashlamp pumped Ti:Sapphire head to further amplify the output of our system, producing 90 fsec, 250 mJ pulses at 5 Hz. The excellent output spatial profile yields a near diffraction-limited 5 micrometers spot size and peak irradiance in excess of 5 X 10¹⁸ W/cm².

The properties of a laser influence the interaction of the intense laser light with materials. We describe some of the diagnostics that we have implemented at the Los Alamos Bright Source to correlate the changes in the x-ray spectrum and temporal history of laser generated silicon plasmas with the changes of the incident XeCl laser light. One property of special interest is the multiple pulsing of the laser on top of the few ns long ASE prepulse. We find that an early pulse enhances the generation of the x rays from a later pulse.

We have demonstrated a system for subpicosecond, soft-x-ray continuum, pump-probe absorption spectroscopy. Using multiphoton ionization to abruptly change the x-ray absorption spectra of a gas, we have measured the temporal profile of laser-generated x-ray pulses near 90 eV. Although the x-ray pulses from a laser-generated plasma here were only as short as approximately 20 psec, the technique is extendible to higher energy x rays that will have pulse durations approaching 100 fsec. We also present the absorption spectrum of Kr ions produced under conditions of high intensity non-resonant multiphoton ionization. The spectra are identified with a fit to the Cowan code.

Plasma-induced self-phase modulation and cross-phase modulation in rare gases and air have been investigated using a femtosecond KrF excimer laser focused to peak intensities in the range 10¹⁴ - 10¹⁵ W cm^-2. Spectral blueshifts of up to 2 nm are observed in the KrF laser spectrum which can be qualitatively modeled by assuming tunneling ionization and one-dimensional pulse propagation. When the degree of ionization Z << 1, pump-probe experiments and theoretical results indicate that field ionization occurs over a time equal to about half the pump pulse width. The pump-probe experiments also show that spatial defocusing causes the spectral blueshifting to be spatially dependent, in agreement with a two dimensional pulse propagation model. Plasma-induced cross-phase modulation can also be used to characterize the pulse width and chirp of an ultrashort laser pulse.

We discuss the use and importance of phase-sensitive pulse diagnostics for the optimization of ultrafast lasers and for implementing quantum control. Knowledge of the exact phase structure is needed in order to determine the phase and amplitude transformations that are required to produce a desired tailored pulse. A special case of pulse shaping is the phase and amplitude compensation of amplified pulses to yield transform-limited pulses. Full intensity and phase measurements of a kHz amplified femtosecond laser system are presented. These measurements provide considerable information about the phase structure which is acquired during amplification and the changes needed to minimize the pulse width. In addition, a versatile light pulse synthesizer which is currently under development is described for producing amplified femtosecond pulses tailored in phase and amplitude.

An external ring cavity containing as its active medium a pair of InGaAsP diodes is modelocked to produce picosecond pulses. In such a laser, a small frequency difference proportional to the nonreciprocal phase shift (resulting from, e.g., the Sagnac effect) can be observed by beating together the counterpropagating laser arms; the device therefore acts as a rotation sensor. In contrast to a conventional (cw) ring laser gyroscope, the pulsed gyroscope can avoid gain competition, thereby enabling the use of homogeneously broadened gain media like semiconductor diodes. Temporal separation of the pulses within the cavity also discriminates against frequency locking of the lasers. The picosecond pulsed diode ring laser gyroscope is reviewed. Both active and passive modelocking are discussed.

We have developed a general technique that combines the temporal resolution of ultrafast laser spectroscopy with the spatial resolution of scanned probe microscopy (SPM). Using this technique with scanning tunneling microscopy (STM), we have obtained simultaneous 2 ps time resolution and 50 angstrom spatial resolution. This improves the time resolution currently attainable with STM by nine orders of magnitude. The potential of this powerful technique for studying ultrafast dynamical phenomena on surfaces with atomic resolution is discussed.

We present femtosecond resolution measurements that demonstrate the occurrence of the ac Stark effect in glass samples doped with CdSSe nanocrystallites. The sample is excited by a 50 fs pulse 80 meV below the band edge. The absorption edge shifts tracking the profile of the pumping pulse. At intensities below 0.5 GW/cm² the edge shift is linear in the pump intensity. Above this value the shift tends to saturate. We also studied CdTe quantum dots in a glass matrix excited resonantly with the 1S - 1S transition. In this case we observe the dynamics of hole relaxation in the valence band. The hole population equilibrates with a time constant of less than 100 fs.

Based on the theory of time-resolved spectrum, a time-resolved optical system is set up with analysis to this optical system in this paper. A detailed discrn;sion is made to the experimental structure on this system, dealing with the non--Jinear opticul phenomena and the light absorption saturation of Al=Ga:J.-xAs compound semiconductor within different x values. Our conclusion is that the electrons scattering in conduction band are due to the interaction between electrons and photons, phonons,defects and ionized impurities, whereas the interaction between electrons and phonons decreases the relative intensity of absorption of photons by electrons. 'fhe slow attenuation process contains various recombination mechanisms, with a relaxation process of about 200 ps.

A new method to describe the self-mode-locking process in femtosecond light generators is formulated based on stability and dynamics analysis for solitons in an equivalent continuous nonlinear medium. A novel type of dissipative optical solitons balanced due to the counteraction of gain nonlinearity and group velocity dispersion is predicted. These solitons feature the process of self-tuning of radiation spectra in the frequency domain towards the gain band edge or the frequency of zero-group-velocity dispersion. The effects of soliton interconversion and shortening to the minimum possible duration, which associate to the self- tuning phenomena, are investigated.