Highly-dispersive mirrors reach new levels of dispersion

Design, production, and characterization of a pair of positive and negative high dispersive mirrors for chirped pulse amplification systems

We report a novel modified Gires-Tournois interferometer (MGTI) starting design for high-dispersive mirrors (HDMs). The MGTI structure combines multi-G-T and conjugate cavities and introduces a large amount of dispersion while covering a wide bandwidth. With this MGTI starting design, a pair of positive (PHDM) and negative highly dispersive mirrors (NHDM) providing group delay dispersions of +1000 fs² and -1000 fs² in the spectral range of 750 nm to 850 nm is developed. The pulse stretching and compression capabilities of both HDMs are studied theoretically by simulating the pulse envelopes reflected from the HDMs. A near Fourier Transform Limited pulse is obtained after 50 bounces on each positive and negative HDM, which verifies the excellent matching between the PHDM and NHDM. Moreover, the laser-induced damage properties of the HDMs are studied using laser pulses of 800 nm and 40 fs. The damage thresholds of the PHDM and NHDM are approximately 0.22 J/cm² and 0.11 J/cm², respectively. The laser-induced blister structure of the HDMs is observed, the formation and evolution processes of the blister are evaluated.

Second and third-order dispersion compensating mirror pairs for the spectral range from 1.2-3.2µm

We demonstrate the design, production, characterization and application of two dispersive complementary mirror pairs compensating second- and third-order dispersion, respectively. Both mirror pairs operate in the spectral range from 1.2-3.2µm. This is an unprecedented bandwidth of over 1.4 octaves which can drive further improvements in Cr:ZnS, Cr:ZnSe and other laser systems with a central wavelength around 2µm. The first pair provides a constant group delay dispersion of -100fs², while the second one enables the compensation of the third-order dispersion that is introduced by a TiO₂ crystal.

3-6 µm dispersive mirrors compensating for dispersion introduced by the GaAs crystal

A new broadband dispersive mirror (DM), which consists of Si and SiO₂ layer materials operating in the spectral range of 3-6 µm, is developed for the first time, to our knowledge. The DM is able to compensate for the dispersion of a 0.5 mm thick GaAs crystal per bounce. Pulse analysis proves that the compensation effect of the DM is much better than a CaF₂ plate, which is the commonly used dispersion compensation element in mid-infrared optical parametric oscillators (MIR OPOs), and the new MIR DM could improve the MIR OPO spectrum with better pulse quality and short pulse duration.

Design, fabrication and measurement of highly-dispersive mirrors with total internal reflection

High group delay dispersion (GDD) is often required for ultrafast laser applications. To achieve GDD level higher than -10000 fs² in a single mirror setting is difficult due to the high sensitivity to unavoidable production inaccuracies. To overcome the problem, total internal reflection (TIR) based dispersive mirrors have been proposed in theory. In this paper, we report our continuous effort to further design, fabricate and measure TIR based dispersive mirrors.

Angle-adjustment-based tunable chirped mirrors with continuous dispersion compensation

We report the feasibility of continuously tunable dispersion control with chirped mirrors (CMs). The concept of tunable second-order and higher-order dispersion is also proposed. Our prototype dispersion-tunable CM makes it possible to provide continuous dispersion support, advancing the CM technique to a new level by overcoming the drawback of the discrete dispersion compensation nature of traditional CMs. This brings extreme convenience and flexibility to the compensation of the dispersion and ensures tailored dispersion compensation in ultrafast laser systems. In our proof-of-concept study, continuously tunable group delay dispersion (GDD) is achieved by altering the angles of incidence on the mirrors. Moreover, continuous duration tunable laser pulses are demonstrated by applying our GDD-tunable CMs in an ultrafast laser system.

Complementary Si/SiO2 dispersive mirrors for 2-4 µm spectral range

Complementary pair of dispersive multilayers operating in the 2-4 µm spectral range were designed and produced for the first time. The mirrors comprise layers of Si and SiO₂ thin-film materials. The pair exhibits unparalleled reflectance exceeding 99.7% and provides a group delay dispersion of (-200) fs². The mirrors can be used in Cr:ZnS/Cr:ZnSe femtosecond lasers and amplifiers.

2/3 octave Si/SiO2 infrared dispersive mirrors open new horizons in ultrafast multilayer optics

Dispersive mirrors operating in a broadband infrared spectral range are reported for the first time. The mirrors are based on Si/SiO₂ thin-film materials. The coatings exhibit reflectance exceeding 99.6% in the spectral range from 2 to 3.2 µm and provide a group delay dispersion of -100 fs² and -200 fs² in this range. The fabricated mirrors are expected to be key elements of Cr:ZnS/Cr:ZnSe femtosecond lasers and amplifiers. The mirrors open a new avenue in the development of ultrafast dispersive optics operating in the infrared spectral range.

Micromirrors with controlled amplitude and phase

This paper describes the fabrication of circular micromirrors with diameters between 50 and 150 μm with controlled amplitude and phase. Design, manufacturing, and characterization method are presented.

High dispersive mirrors for erbium-doped fiber chirped pulse amplification system

We report on the development of near-infrared high dispersive mirrors (HDM) with a group delay dispersion (GDD) of -2000 fs². A HDM pair based on one optimized result at two reference wavelengths (1550 nm and 1560 nm) can reduce the total oscillation of the GDD effectively in the wavelength range of 1530-1575 nm. This HDM pair is designed and fabricated in a single coating run by means of the nonuniformity in film deposition. For the first time, near-infrared HDMs with two different reference wavelengths have been successfully applied in an erbium-doped fiber chirped pulse amplification system for the compression of 4.73 ps laser pulses to 380 fs.