In this Letter, we investigate the resolution of two-photon polymerization (2PP) with an amplified mode-locked external cavity diode laser with adjustable pulse length and a high repetition rate. The experimental results are analyzed with a newly developed 2PP model. Even with low pulse peak intensity, the produced structural dimensions are comparable to those generated by traditional 2PP laser sources. Thus, we show that a compact monolithic picosecond laser diode without amplification and with a repetition rate in the GHz regime can also be applied for 2PP. These results show the high application potential of compact mode-locked diode lasers for low-cost and compact 2PP systems.

Asynchronous optical sampling terahertz time-domain spectroscopy using semiconductor laser-based ultra-short pulse sources is demonstrated. A pair of hybridly mode-locked edge-emitting external cavity lasers operating at a wavelength of 830 nm is used. Terahertz traces with spectral components over a range of 250 GHz are achieved.

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A slotted Y‐branch laser diode that emits two spectral modes at a difference frequency of about 1 THz is investigated in the context of photonic based cw‐THz measurements. The beating frequency of the emitted laser light can be tuned by ±10.5 GHz around 1 THz by changing the applied laser current, which allows for potentially fast measurements. A second spectral window of ±6.5 GHz was found at 850 GHz. Pointwise scanning of the difference frequency is demonstrated with thickness determination of HRFZ‐Si wafer samples as a possible application scenario.