The advancement of contemporary ultrafast science requires reliable sources to provide high-energy few-cycle light pulses. Through experiments and simulations, we demonstrate an arrangement of pulse postcompression, referred to as cascaded focus and compression (CASCADE), for generating millijoule-level, single-cycle pulses in a compact fashion. CASCADE is realized by a series of foci in matter, whereas pulse compression is provided immediately after each focus to maintain a high efficiency of spectral broadening. By implementing four stages of CASCADE in argon cells, we achieve 50-fold compression of millijoule-level pulses at 1030 nanometers from 157 to 3.1 femtoseconds, with an output pulse energy of 0.98 millijoules and a transmission efficiency of 73%. When driving high harmonic generation, these single-cycle pulses enable the creation of a carrier-envelope phase-dependent extreme ultraviolet continuum with energies extending up to 180 electron volts, providing isolated attosecond pulses at the output.

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A 6.29 nW temperature-to-digital converter for infrared (IR) radiation-based thermopile temperature sensors was designed and fabricated on the chip area of 0.068 mm^2 using the 90 nm CMOS technology. The sub-mV voltage produced by the sensor nearly proportional to the temperature difference between the object and the environment is converted to sub-nA current using the gate-leakage characteristics of PMOS transistors. The ratio of the sub-nA current and the reference current proportional to the sub-mV voltage difference is converted to the frequency ratio of the two current-to-frequency oscillators. Then, the digital output proportional to the tiny voltage difference can be obtained by the counters. After the two-point calibrated digital outputs are mapped to the object temperatures, the average resolution is 0.11ºC with the conversion time of 348 ms, which results in the figure of merit (FoM) of 0.026 nJ׺C^2. The inaccuracy is +0.18/-0.98ºC for the object temperatures from -10ºC to 100ºC at the ambient temperature of 25ºC.

By focusing conventional 1-TW 40-fs laser pulses into a dense 450- μm-long nitrogen gas cell, we demonstrate the feasibility of routinely generating electron beams from laser wakefield acceleration (LWFA) with primary energies scaling up to 10 MeV and a high charge in excess of 50 pC. When electron beams are generated with a charge of ≈30 pC and a beam divergence of ≈40 mrad from the nitrogen cell having a peak atom density of [Formula: see text] cm−3, increasing the density inside the cell by 25%—controlled by tuning the backing pressure of fed nitrogen gas—can induce defocusing of the pump pulse that leads to a twofold increase in the output charge but with a trade-off in beam divergence. Therefore, this LWFA scheme has two preferred regimes for acquiring electron beams with either lower divergence or higher beam charge depending on a slight variation of the gas/plasma density inside the cell. Our results identify the high potential for implementing sub-millimeter nitrogen gas cells in the future development of high-repetition-rate LWFA driven by sub-TW or few-TW laser pulses.

We demonstrate the feasibility of using 1-TW, 40-fs laser pulses to generate electrons with peak energy ≈ 9.4 MeV and charge ≈ 32 pC through the laser wakefield acceleration in a dense, 450-µm long nitrogen gas cell.