| Laser is a major invention of mankind since the 20 th century after nuclear energy,computers,and semiconductors.It is called "the sharpest blade","the most accurate ruler",and "the brightest light".As one of the most important members of the laser family,pulsed lasers have been widely used in manufacturing,scientific research,medical,military and other industries because of its high energy and narrow pulse.In the process of passively pulsed laser generation,a key device-saturated absorber is required.The mature commercial semiconductor saturated absorption mirror(SESAM)is difficult to apply on a large scale,restricted by its complicated manufacturing process,high prices and limited response waveband.In recent years,2D material saturated absorbers represented by graphene have received extensive attention due to its simple manufacturing process,low cost,and wide response waveband.At present,2D material saturable absorbers such as graphene,transition metal sulfides and black phosphorus have been widely used in the generation of pulsed lasers.However,these saturable absorbers still have shortcomings such as low absorption rate,limited bandwidth,easy oxidation,and low damage threshold;making it difficult to apply to high-power all-solid-state lasers,especially all-solid-state mode-locked lasers.Therefore,the exploration of a new type of 2D material saturable absorbers is still in progress.In view of the above questions,this paper focuses on the new narrow bandgap 2D materials.By changing the ratio of material elements,controlling the number of layers,exploring different phases and different combination structures and other means,we have successfully broadened the light response range and effectively enhanced the light modulation ability of the existing 2D material saturable absorber.And it is applied to all solid-state pulsed lasers to realize the Q-switched and mode-locked operation.The research content is of great significance for exploring new 2D materials optoelectronic functional devices and promoting the development of all-solid-state pulsed lasers.The main research contents of this paper are as follows:The intrinsic bandgap of transition metal sulfide MoTe2 and PtSe2 was successfully reduced by adjusting the ratio of elements and controlling the number of layers,thereby broadening the optical response waveband of these two materials to the mid-infrared range.The MoTe2 and PtSe2 saturable absorber were prepared through liquid-phase exfoliation and chemical vapor deposition method respectively.Then,all-solid-state 2.0 ?m passively Q-switched laser based on these two saturable absorbers were realized.(Chapter 3)A high-quality 1T-TiSe2 saturated absorber was prepared by the liquid-phase exfoliation method.The third-order nonlinear optical properties of the saturable absorber at the wavelength of 1.0,1.3,2.0 and 2.8 ?m were characterized by I-scan and open-aperture Z-scan methods,which proved the sample has a strong saturated absorption effect at the above wavelengths.Based on the prepared 1T-TiSe2 saturable absorber,all-solid-state passively Q-switched lasers at the above wavelength and 1.0?m Q-switched mode-locked laser were realized.(Chapter 4)The third-order nonlinear optical properties and ultrafast dynamics properties of the zero-bandgap ternary chalcogenide material Ta2NiSe5 were studied.It is proved that it has excellent saturated absorption characteristics and picosecond recovery time,which is enough to support laser pulses in the order of hundreds of femtoseconds.The Ta2NiSe5 saturable absorber was prepared by the liquid-phase exfoliation method.The passively Q-switched lasers at the wavelength of 1.0,2.0 and 2.8 ?m and 1.0 ?m femtosecond-level continuous wave mode-locked laser baesd on the saturable absorber were realized.(Chapter 5)The graphene-like material tellurene(Te)and black phosphorus(BP)are compounded to form the BP/Te heterojunction saturated absorber by the liquid-phase exfoliation method.The third-order nonlinear optical properties of the saturable absorber at the wavelength of 1.0,2.0 and 2.8 ?m were characterized by I-scan and opean aperture Z-scan methods.The all-solid-state Q-switched lasers at the above wavelength and 2.8 ?m and femtosecond-level continuous wave 1.0 ?m mode-locked laser were realized based on the BP/Te heterojunction saturable absorber.Meanwhile,compared with the mono-element Te saturated absorber,it is proved that the heterojunction saturable absorber has more excellent nonlinear optical performance and pulsed laser generation characteristics.(Chapter 6)... |
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