Ultrashort Pulse Research Papers - Academia.edu (original) (raw)

Polarization modulation (PolM) is an interesting alternative for generating transmissions at high bit rate in metropolitan-fiber optical link. In this paper, an optical communications system with PolM and an ultrashort pulse source as... more

Polarization modulation (PolM) is an interesting alternative for generating transmissions at high bit rate in
metropolitan-fiber optical link. In this paper, an optical communications system with PolM and an ultrashort pulse
source as carrier are proposed to carry out a transmission at 190 km in standard single-mode fiber (SSMF). The goal is
to observe the impact of the interaction of polarization-mode dispersion (PMD) and self-phase modulation (SPM) in the
reception. The simulation tests are carried out for a bit rate of 10 and 40 Gb/s, and a power peak ranging from 1 to 50
mW. The optical communications system performance is analyzed by pulse width measurement (carrier), Poincaré
spheres for each phenomenon and with the interaction, eye diagrams and BER vs power curves. The obtained results
show the interaction PMD and SPM is strong at 40 Gb/s and 50 mW where the polarization states (SOP) are spread
with respect to the initial SOP and BER is sufficiently high to reduce the quality of the reception link. The simulations
allow corroborating that the interaction PMD and SPM must not be ignored in optical communications systems with
PolM and the need for developing new mitigation techniques are required.

Millimeter-wave radars offer a practical solution to distinguish objects made of different materials, shapes, and compositions. In this work, radar classification of various materials is demonstrated using a broadband millimeter-wave CMOS... more

Millimeter-wave radars offer a practical solution to distinguish objects made of different materials, shapes, and compositions. In this work, radar classification of various materials is demonstrated using a broadband millimeter-wave CMOS integrated receiver. The receiver is used to record the transmitted power through multiple solid materials at various distances from the receiver in the W-band (75-110 GHz). Three supervised machine learning tools are trained by the recorded data to classify these materials into different categories. The trained classifiers were used to predict material and thickness of objects with varying distances from the receiver with accuracy levels of higher than 96% in material classification and 88% in thickness classification.

Novel materials, notably quantum-dot (QD) semiconductor structures offer the unique possibility of combining exploitable spectral broadening of both gain and absorption with ultrafast carrier dynamic properties. Thanks to these... more

Novel materials, notably quantum-dot (QD) semiconductor structures offer the unique possibility of combining exploitable spectral broadening of both gain and absorption with ultrafast carrier dynamic properties. Thanks to these characteristics QD-based devices have enhanced the properties of ultrashort pulse lasers and opened up new possibilities in ultrafast science and technology. In this paper we will review recent results, which demonstrate that quantum-dot structures can be designed to provide compact and efficient ultrashort pulse laser sources with extremely high and low repetition rates.

Günümüzde lazer teknolojisinin kullanım alanları her geçen gün artarken, fiber lazer de eşsiz teknik özellikleri sayesinde bu pazardaki etkisini sürekli artırmaktadır. Termal etkilerin azaltılmasının önemli olduğu metal delme işlemleri,... more

Günümüzde lazer teknolojisinin kullanım alanları her geçen gün artarken, fiber lazer de eşsiz teknik özellikleri sayesinde bu pazardaki etkisini sürekli artırmaktadır. Termal etkilerin azaltılmasının önemli olduğu metal delme işlemleri, güneş hücrelerinin kesilmesi veya şekillendirilmesi, kalp stentlerinin mikro işleme yöntemleri ile şekillendirilmesi, görüntüleme ekranları ve diğer birçok materyal üzerine yapılan uygulamalarda ultrahızlı lazerler günümüzde her geçen gün daha fazla tercih edilmektedirler.

We investigate the possibility of using poled silica photonic crystal fibers for self-defocusing soliton compression with cascaded quadratic nonlinearities. Such a configuration has promise due to the desirable possibility of reducing the... more

We investigate the possibility of using poled silica photonic crystal fibers for self-defocusing soliton compression with cascaded quadratic nonlinearities. Such a configuration has promise due to the desirable possibility of reducing the group-velocity mismatch. However, this unfortunately leads to increased phase mismatch, and the dispersion is often anomalous. All this reduces the design parameter space where soliton compression is possible, and poses strong requirements on the poling efficiency. We propose to use quasi-phase matching in order to reach realistic requirements on the quadratic nonlinearity, and show that compression of nJ pulses to few-cycle duration is possible in such a fiber. A small amount of group-velocity mismatch optimizes the compression.

In this work, by using 4x4 ray-pulse matrices, we analyze the influence of the position of the output diffraction grating in 4f- and 2f-2f-systems with respect to the eventually introduced group-delay dispersion, spatial and angular... more

In this work, by using 4x4 ray-pulse matrices, we analyze the influence of the position of the output diffraction grating in 4f- and 2f-2f-systems with respect to the eventually introduced group-delay dispersion, spatial and angular chirp. We show that in the 4f-configuration, in contrast to the 2f-2f-setup, the grating offset does not cause angular chirp and pulse front tilt. We theoretically derive an expression for the interferometric autocorrelation signal in the presence of an arbitrary pulse-front tilt.

Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd: YAG... more

Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd: YAG ceramic laser in 1995, ...

We consider the coupling of two optical waveguides in the few-cycle regime. The analysis is performed in the frame of a generalized Kadomtsev-Petviashvili model. A set of two coupled modified Korteweg–de Vries equations is derived, and it... more

We consider the coupling of two optical waveguides in the few-cycle regime. The analysis is performed in the frame of a generalized Kadomtsev-Petviashvili model. A set of two coupled modified Korteweg–de Vries equations is derived, and it is shown that three types of coupling can occur, involving the linear index, the dispersion, or the nonlinearity. The linear nondispersive coupling is investigated numerically, showing the formation of vector solitons. Separate pulses may be trapped together if they have not initially the same location, size, or phase, and even if their initial frequencies differ.

We present new approaches for power scaling and tunability in semiconductor disk lasers. The novel concepts allow for reduced thermal load of the gain material, increasing the threshold of rollover and extending the capability for... more

We present new approaches for power scaling and tunability in semiconductor disk lasers. The novel concepts allow for reduced thermal load of the gain material, increasing the threshold of rollover and extending the capability for boosting the output power without significant degradation in the beam quality. The proposed technique for power scaling of optically-pumped semiconductor disk lasers is based on the multiple gain scheme. The method allows for significant power improvement while preserving good beam quality. Total power of over 8 W was achieved in dual-gain configuration, while one-gain lasers could produce separately about 4 W, limited by the thermal rollover of the output characteristics. The results show that reduced thermal load to a gain element in a dual-gain cavity allows extending the range of usable pump powers boosting the laser output. Tunable Sb-based semiconductor disk laser operating at 2-mum is demonstrated with nearly 100 nm operation range. The maximum outp...

A novel device designed for pulse shaping, characterization and phase compensation in ultrafast laser systems is described. The pulse shaper exhibits low transmission loss and is widely applicable to lasers with spectral bandwidth from 10... more

A novel device designed for pulse shaping, characterization and phase compensation in ultrafast laser systems is described. The pulse shaper exhibits low transmission loss and is widely applicable to lasers with spectral bandwidth from 10 nm to over 400 nm. Pulse characterization and phase compensation is fully computer controlled in a closed loop via MIIPS method. This system is designed

ABSTRACT Ultrafast lasers are suitable for different surgical procedures in the eye: As a main goal in our group, the application of fs-lasers in refractive surgery is studied. Therefore,experiments in living rabbits were conducted, with... more

ABSTRACT Ultrafast lasers are suitable for different surgical procedures in the eye: As a main goal in our group, the application of fs-lasers in refractive surgery is studied. Therefore,experiments in living rabbits were conducted, with wound healing studies up to 120 ays after surgery. Moreover,highly precise cuts inside the cornea were used to do keratoplasty an lamellar keratoplasty. Further applications like a new technique to overcome presbyopia are shown.