Dispersion-managed Breathing-mode Semiconductor Mode-locked Ring Laser

A novel dispersion-managed breathing-mode semiconductor mode-locked ring laser is developed. The breathing-mode designation derives from the fact that intracavity pulses are alternately stretched and compressed as they circulate around the ring resonator. The pulses are stretched before entering the semiconductor gain medium to minimize the detrimental strong integrating self-phase modulation and to enable efficient pulse amplification. Subsequently compressed pulses facilitate bleaching the semiconductor saturable absorber. The intracavity pulse compression ratio is higher than 50. Down chirping when compared to up chirping allows broader mode-locked spectra and shorter pulse generation owing to temporal and spectral semiconductor gain dynamics. Pulses as short as 185 fs, with a peak power of ~230 w, and a focused intensity of ~4.6 gw/cm2 are generated by linear down chirp compensation and characterized by shg-frog method. To our knowledge, this is the highest peak power and the shortest pulse generation from an electrically pumped all-semiconductor system. The very good agreement between the simulated and the measured results verifies our understanding and ability to control the physical mechanisms involved in the pulse shaping within the ring cavity. Application trends such as continuum generation via a photonic crystal fiber, two-photon fluorescence imaging, and ultrafast pulse source for pump-probe experiments are demonstrated

Extreme Chirped/ Stretched Pulsed Amplification and Laser DIVB

Methods, devices and systems for generating ultrashort optical linear chirped pulses with very high power by amplifying the pulses so that their temporal duration is longer than the storage time of the amplifying medium. The additional gain factor is related to the ratio of the storage time to the stretched pulse. A preferred embodiment connects a mode locked laser source that generates optical pulses whose duration is stretched with a chirped fiber Bragg grating. Embodiments include methods, devices and systems causing an extreme chirped pulse amplifier (XCPA) effect in an oscillator

Extreme Chirped/Stretched Pulsed Amplification and Laser

Methods, devices and systems for generating ultrashort optical linear chirped pulses with very high power by amplifying the pulses so that their temporal duration is longer than the storage time of the amplifying medium. The additional gain factor is related to the ratio of the storage time to the stretched pulse. A preferred embodiment connects a mode locked laser source that generates optical pulses whose duration is stretched with a chirped fiber Bragg grating. Embodiments include methods, devices and systems causing an extreme chirped pulse amplifier (XCPA) effect in an oscillator

Extreme Chirped/Stretched Pulsed Amplification and Laser DIV.

Methods, devices and systems for generating ultrashort optical linear chirped pulses with very high power by amplifylng the pulses so that their temporal duration is longer than the storage time of the amplifying medium. The additional gain factor is related to the ratio of the storage time to the stretched pulse. A preferred embodiment connects a mode locked laser source that generates optical pulses whose duration is stretched with a chirped fiber Bragg grating. Embodiments include methods, devices and systems causing an extreme chirped pulse amplifier (XCPA) effect in an oscillator

Laserom inducirana fluorescencija stanja A 1Σu+ molekule Li2

By using several continuous wave (CW) single longitudinal-mode semiconductor laser diodes in the red spectral region, we have excited Li2 molecule from the X 1Σ g+ state to the A 1Σu+ state (transitions: (v " = 0, J " = 19) → (v\u27 = 4, J\u27 = 18); (v " = 1, J " = 9) → (v\u27 = 5, J\u27 = 10); (v " = 2, J " = 9) → (v\u27 = 10, J\u27 = 10)) and observed the fluorescence of the resonance A → X lines together with collision induced lines. Comparison with theoretical simulations shows a very good agreement. The use of two or three diode lasers is discussed in view of two- or three-step excitation of Li2 molecule to the higher Rydberg or ionized molecular states.Pomoću kontinuiranih jednomodnih lasera u crvenom dijelu spektra pobuđivali smo molekulu Li2 iz stanja X 1Σg+ u stanje A 1Σu+ (v " = 0, J " = 19) → (v\u27 = 4, J\u27 = 18); (v " = 1, J " = 9) → (v\u27 = 5, J\u27 = 10); (v " = 2, J " = 9) → (v\u27 = 10, J\u27 = 10)) i promatrali fluorescenciju rezonantnih A → Xprijelaza zajedno sa sudarom uzrokovanim prijelazima. Usporedba eksperimentalnih spektara s teorijskim simulacijama tih spektara pokazuje dobro slaganje. Diskutira se upotreba dva ili tri diodna lasera za trokoračno pobuđenje molekule Li2 u viša Rydbergova ili ionizirana stanja

Laserom inducirana fluorescencija stanja A 1Σu+ molekule Li2

By using several continuous wave (CW) single longitudinal-mode semiconductor laser diodes in the red spectral region, we have excited Li2 molecule from the X 1Σ g+ state to the A 1Σu+ state (transitions: (v " = 0, J " = 19) → (v\u27 = 4, J\u27 = 18); (v " = 1, J " = 9) → (v\u27 = 5, J\u27 = 10); (v " = 2, J " = 9) → (v\u27 = 10, J\u27 = 10)) and observed the fluorescence of the resonance A → X lines together with collision induced lines. Comparison with theoretical simulations shows a very good agreement. The use of two or three diode lasers is discussed in view of two- or three-step excitation of Li2 molecule to the higher Rydberg or ionized molecular states.Pomoću kontinuiranih jednomodnih lasera u crvenom dijelu spektra pobuđivali smo molekulu Li2 iz stanja X 1Σg+ u stanje A 1Σu+ (v " = 0, J " = 19) → (v\u27 = 4, J\u27 = 18); (v " = 1, J " = 9) → (v\u27 = 5, J\u27 = 10); (v " = 2, J " = 9) → (v\u27 = 10, J\u27 = 10)) i promatrali fluorescenciju rezonantnih A → Xprijelaza zajedno sa sudarom uzrokovanim prijelazima. Usporedba eksperimentalnih spektara s teorijskim simulacijama tih spektara pokazuje dobro slaganje. Diskutira se upotreba dva ili tri diodna lasera za trokoračno pobuđenje molekule Li2 u viša Rydbergova ili ionizirana stanja

Laser surface structuring with 100W of average power and sub-ps pulses

High throughput still represents a key factor for industrial use of ultrashort pulses in the field of surface structuring. Reliable systems with average powers up to 100W are today available. It has already been proved that metals, especially steel having a low threshold fluence, can be machined with excellent surface quality at average powers of more than 40W and a spot radius of about 25lm, if a polygon line scanner, offering fast scanning speeds, is used. A further scale-up into the 100W regime should be possible for metals showing a threshold fluence of about 0.2 J/cm2 or higher. But, it will lead to problems with heat accumulation in the case of steel and a straight forward scale-up is not possible. In order to keep a good surface quality, the machining strategy has to be adapted. A maximum flexibility can be obtained with an “interlaced” mode by using very high marking speeds of several 100m/s and repetition rates of several tenths of MHz. As this is at the edge of today available technologies, alternative strategies are additionally investigated. Enlarging the spot size represents the most simple approach to reduce the heat accumulation in the case of steel but also multispots represent an attractive alternative

Do Nutrition Habits Influence on Parkinson`\u27s Disease Clinical Presentation?

Introduction: Parkinson\u27s disease (PD) is the second most common neurodegenerative disorder characterized with alpha-synuclein pathology. For the majority of patients, except for some genetic forms, etiology is still unknown. There are some implications that food intake and gut microbiota could contribute to PD. Aim: The aim of this paper is to analyze the influence of protein, fruit and vegetable intake on the clinical presentation of idiopathic Parkinson disease Patients and methods: Patients with idiopathic PD were surveyed for demographic data and nutritional habits in regards to protein, fruit and vegetable intake. Motor symptoms were evaluated using the Unified Parkinson Disease Rating Scale (UPDRS) part III and IV, cognitive impairment using Mini Mental State Examination (MMSE) and depression using Beck Depression Inventory (BDI). Results: We have analyzed data of 96 patients. Patients using fewer dairy products have more often tremor type of PD (p<0.040). We did not find any differences in severity of motor symptoms, disease stage, age when disease start, frequency of motor complications and fluctuation of therapy, depression and cognitive impairment according to protein, fruit and vegetable ingestion. Conclusion: Higher intake of dairy products could influence the appearance of less favorable forms of Parkinson\u27s disease (rigor type). Protein, fruit and vegetable intake do not influence the disease appearance, severity of motor symptoms, motor fluctuation and complication of therapy, disease stage, the appearance of cognitive impairment nor depression in Parkinson\u27s disease patients. (Tomic S, Pekic V, Popijac Z, Pucic T, Petek Vinkovic M, Popovic Z, Resan B, Gilman Kuric T. Do Nutrition Habits Influence the Clinical Presentation of Parkinson’s Disease?. SEEMEDJ 2019; 3(2); 11-21

Two-photon fluorescence imaging with 30 fs laser system tunable around 1 micron

We developed a low-cost, low-noise, tunable, high-peak-power, ultrafast laser system based on a SESAM-modelocked, solid-state Yb tungstate laser plus spectral broadening via a microstructured fiber followed by pulse compression. The spectral selection, tuning, and pulse compression are performed with a simple prism compressor. The output pulses are tunable from 800 to 1250 nm, with the pulse duration down to 25 fs, and average output power up to 150 mW, at 80 MHz pulse repetition rate. We introduce the figure of merit (FOM) for the two-photon and multi-photon imaging (or other nonlinear processes), which is a useful guideline in discussions and for designing the lasers for an improved microscopy signal. Using a 40 MHz pulse repetition rate laser system, with twice lower FOM, we obtained high signal-to-noise ratio two-photon fluorescence images with or without averaging, of mouse intestine section and zebra fish embryo. The obtained images demonstrate that the developed system is capable of nonlinear (TPE, SHG) imaging in a multimodal operation. The system could be potentially used in a variety of other techniques including, THG, CARS and applications such as nanosurgery