We present a programmable diode laser that can generate arbitrary optical pulse shapes and bursts with a timing resolution of 200 ps and 8 bit resolution for the amplitude level setting of each time bin. A PicoQuant developed ASIC is used as waveform generator. The use of a 5 GHz chip design and close arrangement of optimized electrical interfaces to the laser diode maintain the high frequency signal quality delivered into the laser diode. Fast current slopes result in picosecond gain switched operation while for nanosecond pulses undesired ringing effects at fast switch-on transients are reduced by defining specific current ramps.
Third harmonic 355nm picosecond pulses are generated by sum frequency mixing in a periodically poled magnesium
doped stoichiometric lithium tantalate (PPMgSLT) crystal. The third harmonic generation is based on the
1064nm radiation of a gain-switched distributed feedback (DFB) diode laser which is amplified by a two-stage
fiber amplifier. The diode laser is freely triggerable at variable repetition rates up to 80MHz and provides optical
pulses of 65 ps FWHM duration and pulse energies in the range of 5 pJ. The 355nm third harmonic generation
is realized in a two-step conversion process. First, the 1064nm fundamental radiation is frequency-doubled to
532 nm, afterwards both frequencies are mixed in the PPMgSLT crystal to 355 nm. The UV-radiation shows
a pulse width of 60 ps, a good beam profile and stable pulse energy over a wide range of repetition rates by
proprietary pump power management. At 355nm a pulse peak power of 5.3W was achieved with 192W pulse
peak power of the fundamental radiation.
The optical amplification and frequency conversion of a gain-switched 1532 nm distributed feedback (DFB) laser diode over a wide range of repetition rates are studied. A two stage Erbium fiber amplifier setup is pumped at 976 nm and operated at 1 to 80MHz pulse repetition frequency. The seed laser repetition rate is evaluated directly inside the pumping electronics to set the optimum pump power. Second-harmonic generation to 766 nm is achieved in a periodically poled lithium niobate bulk crystal. There is a high demand of several hundred milliwatt of picosecond pulsed laser power for stimulated emission depletion (STED) microscopy.
An freely triggerable picosecond visible supercontinuum laser source is presented that allows for a uniform spectral
profile and equivalent pulse characteristics over variable repetition rates from 1 to 40MHz. The system features PM Yb3+-doped fiber amplification of a picosecond gain-switched seed diode at 1062 nm. The pump power in
the multi-stage amplifier is actively adjusted by a microcontroller for a consistent peak power of the amplified signal in the full range of repetition rates. The length of the PCF is scaled to deliver a homogeneous spectrum and minimized distortion of the temporal pulse shape.
The fiber amplification of a gain-switched laser diode and subsequent sum-frequency mixing of the signal with the residual emission from the pump diode of the amplifier is presented as a practical and economical source for a gain-switched distributed feedback (DFB) picosecond laser diode emitting at 1532 nm is coupled into an Erbium-doped fiber amplifier (EDFA) that is core-pumped by a narrowband, single-mode laser diode at 976 nm. The length of the active fiber is optimized for achieving amplification to several watts of puled peak power at 1532 nm, while simultaneously allowing for a significant transmission of the residual pump power after the amplifier. The co-propagating amplified signal pulse at 1532 nm and residual pump at 964 nm provide a convenient geometry for direct fiber coupling into a periodically posed potassium titanyl phosphate (PP-KTP) waveguide for sum-frequency generation (SFG) of picosecond pulses at 596 nm. The variable operation of the seed diode allows for a free-running and triggered configuration over a wide range of repetition operation of the seed diode allows for a free-running and triggered configuration over a wide range of repetition rates for 596 nm pulsed emission from 5 to 80 MHz with pulse energies up to 5 pJ at a pulse duration of sub 122 ps.
We present a compact frequency-doubled laser source with fundamental wavelength operation at 1062 nm. A
freely triggerable seed diode laser delivers sub-100 ps pulses in the picojoule range at variable repetition rates
up to 80 MHz. After amplification in a Ytterbium-doped fiber amplifier, the average power exceeds 380mW at
40 MHz, which corresponds to 9.5 nJ pulses and about 75W of peak power. The output beam is then focussed
into periodically poled lithium niobate for second harmonic generation (SHG). In this way, green picosecond
pulses with an energy of up to 2 nJ at 40MHz are generated. The pulse energy and pulse shape of the second
harmonic pulses are systematically studied for various repetition rates, allowing conclusions on the amplifier
performance under different operating conditions.
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