Contents
Source: PicoQuant
Mode-Locked Diode Lasers
Diode lasers can be designed to emit light in ultrashort pulses rather than continuously. This is achieved through mode-locking techniques, where a single ultrashort pulse circulates in the laser resonator, leading to a high repetition rate pulse train. Mode-locked diode lasers can produce pulses in the picosecond regime, with pulse durations typically ranging from a few picoseconds to femtoseconds.
Pulse Properties
Due to the short laser resonators in diode lasers, the resulting pulse repetition rates are high, usually in the gigahertz range. The average output power in mode-locked operation is lower than in continuous-wave operation, with pulse energies typically in the low picojoule region. The pulses are synchronized with an electrical signal and exhibit low timing jitter.
Gain-Switched Laser Diodes
Gain switching is a technique to generate short pulses from laser diodes without an external cavity. By applying short current pulses to the diode, laser operation starts, leading to the generation of well-shaped optical pulses with durations in the tens of picoseconds range. The pulse energy and duration can be controlled by adjusting the current pulses.
Operation Principle and Pulse Energy
Gain-switched laser diodes offer simplicity in pulse generation and can produce pulses on demand. The pulse energy is typically in the tens of picojoules range, with peak powers around 1 W. By optimizing the driving conditions and laser diode selection, the performance of gain-switched lasers can be enhanced.
Applications
Gain-switched laser diodes find applications in laser micromachining, optical parametric amplifiers, fluorescence lifetime measurements, and optical metrology. They offer flexibility in pulse generation for various scientific and industrial applications. When used as seed lasers, they can enhance the output pulse energies and consistency in optical parametric amplifiers.
In conclusion, mode-locked and gain-switched diode lasers provide versatile tools for generating ultrashort pulses with controllable parameters, catering to a wide range of applications in photonics and beyond.
Source: Photon Lines
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