Method for measuring the speed parameters of photodetectors

Wide-spectral saturable absorption (SA) in low-dimensional (LD) nanomaterials such as zero-, one-, and two-dimensional materials has been proven experimentally with outstanding results, including low saturation intensity, deep modulation depth, and fast carrier recovery time. LD nanomaterials can therefore be used as SAs for mode-locking or Q-switching to generate ultrafast fiber laser pulses with a high repetition rate and short duration in the visible, near-infrared, and mid-infrared wavelength regions. Here, we review the recent development of emerging LD nanomaterials as SAs for ultrafast mode-locked fiber laser applications in different dispersion regimes such as anomalous and normal dispersion regimes of the laser cavity operating in the near-infrared region, especially at ~1550 nm. The preparation methods, nonlinear optical properties of LD SAs, and various integration schemes for incorporating LD SAs into fiber laser systems are introduced. In addition to these, externally (electrically or optically) controlled pulsed fiber laser behavior and other characteristics of various LD SAs are summarized. Finally, the perspectives and challenges facing LD SA-based mode-locked ultrafast fiber lasers are highlighted.

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Ultra short pico second chirped pulse generation using SESAM based mode-locked fiber laser

10.31219/osf.io/8tka6 ◽

2019 ◽

Author(s):

Arpan Dutta

Keyword(s):

Fiber Laser ◽

Fiber Lasers ◽

Short Pulse ◽

Mode Locking ◽

Pulse Generation ◽

Short Pulses ◽

Chirped Pulse ◽

Chirped Pulse Amplification ◽

Pulsed Fiber Laser ◽

Ultra Short Pulse

Ultra short pulse fiber lasers are widely used in many photonic systems for industrial, biomedical and scientific applications. Popularity of these lasers rapidly developed due to increment in demand of shorter pulses for various applications like communication, ophthalmology, micromachining, medical imaging and precision metrology. Pulsed fiber laser can produce ultra short pulses in order of pico or femto second. Mode locking technique is widely used in rare earth doped fiber lasers to produce such ultra short pulses of light. In this paper, pulsed operation of fiber laser was studied experimentally at 1 micron region. Experiment on pulsed fiber laser has been done using ytterbium (Yb) doped active fiber. Using the principle of passive mode locking, a 2.3 pico-second pulse was produced at 1064nm wavelength. A semiconductor saturable absorber mirror was used to mode lock the laser. The spectral domain data showed that the pulse was not Fourier transform limited which means the pulse was chirped. Chirped pulse amplification systems exploit this pulse characteristic for power scaling of ultra-short pico- second to femto-second pulses.

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High Power Linearly Polarized Fiber Lasers in a Linear Cavity

10.32920/ryerson.14657970.v1 ◽

2021 ◽

Author(s):

Angie Reda Abdelhay Mohamed Ali Eldamak

Keyword(s):

Theoretical Model ◽

Fiber Laser ◽

High Power ◽

Fiber Lasers ◽

Mode Locking ◽

Gain Medium ◽

The Self ◽

Pulse Envelope ◽

Linear Cavity ◽

Linearly Polarized

This thesis presents two designs for high power linearly polarized all-fiber linear cavity lasers, continuous wave (CW) and mode-locked. The cavity designs use Polarization Maintaining (PM) fibers for both gain medium and Fiber Bragg Gratings (FBGs). The FBG pairs select lasing wavelength and polarization. The fiber lasers incorporating specialty designed FBGs achieve an extinction ratio larger than 23 dB. Firstly, an all-fiber linear cavity design of a high power picoseconds mode-locked laser is introduced. The proposed configuration is based on Non-Linear Polarization (NPR) using PM Yb-doped active fiber and two matching FBGs to form the laser cavity. The combination of nonlinearity, gain and birefringence in cavity made the laser generate mode-locked pulses in picoseconds range and with high average output power. The output mode-locked pulses amplitude is modulated with an envelope whose mechanism is also investigated in this thesis project. Experimental data and numerical simulations of the self mode-locking fiber laser are presented. Main parameters affecting mode-locked pulses and its envelope are identified. In addition, a new theoretical model based on Nonlinear Schrödinger Equation (NLSE) is developed and implemented on the MATLAB platform. The model explains the self mode-locking mechanism and the source of the pulse envelope. In this model, it is proven that self phase modulation (SPM) plays an essential role in pulse formation and shaping. The theoretical model and experimental results are in a very good agreement at different pumping levels. A method of regulating the mode-locked pulses is presented. This is achieved by applying a pulsed current to pump diode. This method successfully stabilizes the mode-locked pulses underneath a Q-switched pulse envelope. Further scale-up of average power and pulse energy is realized by adding an amplifier stage. Secondly, a CW dual-wavelength all-fiber laser is presented. The laser consists of two pairs of FBGs and a PM Er/Yb co-doped fiber as a gain medium. The laser emits at both 1 μm and 1.5 μm wavelengths simultaneously with a stable output. This laser provides a compact fiber-based pumping source that is suitable for mid-IR generation.

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High Power Linearly Polarized Fiber Lasers in a Linear Cavity

10.32920/ryerson.14657970 ◽

2021 ◽

Author(s):

Angie Reda Abdelhay Mohamed Ali Eldamak

Keyword(s):

Theoretical Model ◽

Fiber Laser ◽

High Power ◽

Fiber Lasers ◽

Mode Locking ◽

Gain Medium ◽

The Self ◽

Pulse Envelope ◽

Linear Cavity ◽

Linearly Polarized

This thesis presents two designs for high power linearly polarized all-fiber linear cavity lasers, continuous wave (CW) and mode-locked. The cavity designs use Polarization Maintaining (PM) fibers for both gain medium and Fiber Bragg Gratings (FBGs). The FBG pairs select lasing wavelength and polarization. The fiber lasers incorporating specialty designed FBGs achieve an extinction ratio larger than 23 dB. Firstly, an all-fiber linear cavity design of a high power picoseconds mode-locked laser is introduced. The proposed configuration is based on Non-Linear Polarization (NPR) using PM Yb-doped active fiber and two matching FBGs to form the laser cavity. The combination of nonlinearity, gain and birefringence in cavity made the laser generate mode-locked pulses in picoseconds range and with high average output power. The output mode-locked pulses amplitude is modulated with an envelope whose mechanism is also investigated in this thesis project. Experimental data and numerical simulations of the self mode-locking fiber laser are presented. Main parameters affecting mode-locked pulses and its envelope are identified. In addition, a new theoretical model based on Nonlinear Schrödinger Equation (NLSE) is developed and implemented on the MATLAB platform. The model explains the self mode-locking mechanism and the source of the pulse envelope. In this model, it is proven that self phase modulation (SPM) plays an essential role in pulse formation and shaping. The theoretical model and experimental results are in a very good agreement at different pumping levels. A method of regulating the mode-locked pulses is presented. This is achieved by applying a pulsed current to pump diode. This method successfully stabilizes the mode-locked pulses underneath a Q-switched pulse envelope. Further scale-up of average power and pulse energy is realized by adding an amplifier stage. Secondly, a CW dual-wavelength all-fiber laser is presented. The laser consists of two pairs of FBGs and a PM Er/Yb co-doped fiber as a gain medium. The laser emits at both 1 μm and 1.5 μm wavelengths simultaneously with a stable output. This laser provides a compact fiber-based pumping source that is suitable for mid-IR generation.

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