BOAR: Biprism based optical autocorrelation with retrieval

Abstract

A simple and compact single-shot autocorrelator is presented and analyzed in detail. The autocorrelator is composed of two elements only: a Fresnel biprism used to create two temporally delayed replicas of the pulse to characterize and a camera in which two-photon absorption takes place. The two-photon absorption signal obtained in the camera can be used to retrieve the pulse duration, the frequency chirp, and the pulse spectrum, provided that a Gaussian temporal shape is assumed. Thanks to its extreme simplicity, the autocorrelator is robust and easy to align. The presented design can theoretically characterize the pulse duration from about 25 fs to 1.5 ps in the two-photon spectral range of the camera (1200-2400 nm). Finally, a proof-of-principle demonstration is also performed at 3.1 µm by using an InGaAs camera, whose two-photon spectral range is located further in the infrared (1800-3400 nm).

Spectral phase reconstruction of femtosecond laser pulse from interferometric autocorrelation and evolutionary algorithm

“…The IAC signal is known to contain oscillating terms at ω ≈ 0, ω 0 and 2ω 0 [16,20] which (assuming a perfect balance between the two replicas amplitudes A 1 = A 2 = A) can write as:…”

“…The 1.67 µm pixel size of the sensor allows to resolve the optical fringes in the whole spectral range while the 6.4 mm sensor size of the camera provides a temporal window of 3.5 ps. As explained in [20], special care has been taken to insure that the size of the biprism or the beam extension does not limit the latter in order to benefit from the full temporal window allowed by sensor size. The use of only two elements for this autocorrelator makes the BOAR extremely compact, calibration-free, robust in alignment and almost insensitive to the input polarization [20] since the nonlinear process is not limited by any phase matching consideration.…”

“…As explained in [20], special care has been taken to insure that the size of the biprism or the beam extension does not limit the latter in order to benefit from the full temporal window allowed by sensor size. The use of only two elements for this autocorrelator makes the BOAR extremely compact, calibration-free, robust in alignment and almost insensitive to the input polarization [20] since the nonlinear process is not limited by any phase matching consideration. The set-up is also very sensitive, typical input energy for a single-shot operation is 100 nJ.…”

“…This method has nevertheless been gradually disregarded, probably because of the difficulty in obtaining both reliable IAC and spectrum measurements at the same time. We revisit in this work the strategy of Naganuma et al with a recently developed autocorrelator [20] called biprism based optical autocorrelation with retrieval (BOAR). This last provides a singleshot IAC trace of great reliability and robustness well-suited for a complete reconstruction of ultrashort pulses.…”

TIGER: TIme-Gated Electric field Reconstruction

“…It implies that, at the propagation distance where the four beams overlap, there is direct linear correspondence between the delays (τ 1 , τ 2 ) and the (x, y) coordinates. The four-faced pyramid can then be viewed as a bi-dimensional extension of the Fresnel biprism, which is commonly used in single shot characterization devices for creating two time-delayed replicas in a single spatial dimension [12,13].…”