High-contrast linear optical pulse compression using a temporal hologram

Exploiting the FM-to-AM conversion to generate high-contrast picosecond laser pulses

In this work, we simulate and demonstrate experimentally a new approach to generate picosecond laser pulses. This technique is based on optoelectronic FM-to-AM conversion: a transient radiofrequency phase modulation is applied on a continuous-wave fiber laser otherwise blocked by a bandstop filter. By leveraging the ability of modern electronic amplifiers to generate high voltage swings values on a short timescale, the presented setup induces a large and brief excursion out of the filter, hence generating 18 ps pulses with a time contrast of 38 dB. Detailed simulations pave the road toward pulses shorter than 1 ps by using an optimally shaped RF response.

Several new directions for ultrafast fiber lasers [Invited]

Ultrafast fiber lasers have the potential to make applications of ultrashort pulses widespread - techniques not only for scientists, but also for doctors, manufacturing engineers, and more. Today, this potential is only realized in refractive surgery and some femtosecond micromachining. The existing market for ultrafast lasers remains dominated by solid-state lasers, primarily Ti:sapphire, due to their superior performance. Recent advances show routes to ultrafast fiber sources that provide performance and capabilities equal to, and in some cases beyond, those of Ti:sapphire, in compact, versatile, low-cost devices. In this paper, we discuss the prospects for future ultrafast fiber lasers built on new kinds of pulse generation that capitalize on nonlinear dynamics. We focus primarily on three promising directions: mode-locked oscillators that use nonlinearity to enhance performance; systems that use nonlinear pulse propagation to achieve ultrashort pulses without a mode-locked oscillator; and multimode fiber lasers that exploit nonlinearities in space and time to obtain unparalleled control over an electric field.

Interference-type time lens based on temporal hologram in a loop configuration

An alternative scheme is proposed for implementing a time lens based on the temporal hologram concept. Instead of using edge-pass filtering, this scheme achieves the keeping of only the time-lens (quadratic phase modulation) term of interest through the interference of two modulated component beams. In this scheme, an additional linear frequency component does not have to be added to the electronic drive signal to avoid the overlapping of the target frequency component and its conjugate of the modulated signal. Thus, the proposed hologram-based time lens is not only able to relax the limitation of the bandwidth and sampling rate of the arbitrary waveform generator on the time-bandwidth product and resolution to some extent, but is also capable of processing shorter input pulse signals. These advantages make the proposed interference-type hologram time lens especially suitable for use in a loop configuration, where it can be reused when the signal pulse circulates in the loop. This promises significantly enhanced time-bandwidth product and resolution, and the temporal aperture size can be designed as large as desired theoretically.