Open-source 3D-printed terahertz pulse time-domain holographic detection module

Abstract

We present a holographic detection module to measure the spatially resolved distribution of pulsed terahertz field in a single scan by a motorized translation stage, responsible for the time delay. All mounts of the optical elements of the module are easily reproduced by 3D printing and attached to the optical cage system. The latter greatly simplifies the measurement procedure, allowing the experimenter to move and adjust the detection system as a single device. The developed mounts are made universal and can be used in other setups. We have made 3D models available as open-source hardware. The module is based on an electro-optical detection scheme with wide-aperture ZnTe crystal, crossed polarizers, and a matrix photodetector. The validation of its operability was performed with two experiments to measure the spatial distribution of the unperturbed field from the generator and the vortex field formed by the spiral phase plate. Optical vortices with multiple topological charges of 2–4 were detected on spectral components in the range from 0.3 to 1.1 THz. In addition, we have detailed the alignment process of terahertz imaging systems.

Design of broadband terahertz vector and vortex beams: I. Review of materials and components

“…LC-formed vortex structures were characterised by a holographic imaging system 70 , which is very similar by design to our detection module for THz PTDH manufactured on the basis of 3D-models with open-source codes 161,162 . Despite the fact that LC cells were irradiated by broadband THz radiation, vortex phase distributions are demonstrated for a separate spectral component of 1 THz (or 1.2 THz) only.…”

Design of broadband terahertz vector and vortex beams: II. Holographic assessment

“…In addition, it also can be exploited as an effective 'virtual instrument' to predict specific properties of ultra-fast pulses after their propagation through or reflectance from the specific elements/components/samples. In this paper, we will pay attention to opportunities for numerical wavefront shapers design, while the description of experimental works [24,20,23] and manufacturing of the measurement unit based on 3D-models in open-source codes [25,26], remains beyond the scope of our current consideration.…”

“…These possibilities of numerical research, after the beam shaper manufacturing, can be supplemented by the potential of physical experimental research. Indeed, having an electrooptical detection module [40] available or fabricating it using additive manufacturing methods based on open source 3D models [25,26], it is possible to record the spatiotemporal dependence of the THz field strength in the diffraction zone. Then, by excluding a possible measurement system response (e.g.…”

Single-scan multiplane phase retrieval with a radiation of terahertz quantum cascade laser

“…In this field, THz imaging [1][2][3] represents one of the most promising approaches, since it provides spatially resolved information about the investigated objects. THz phase imaging (THz PI) [4,5], which includes pulse time-domain holography (PTDH) [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] as well as continuous wave (CW) holography [23][24][25][26][27][28][29][30], Hartmann wavefront sensing [31][32][33][34][35], shearorgaphy [36], ptychography [37][38][39][40][41], and other phase retrieval techniques [42][43][44][45][46][47][48][49], ...…”

“…A lot of technical solutions, experimental layouts, and reconstruction algorithms for THz PI have been proposed, and this field is reaching a certain level of maturity [5]. THz PTDH provides ultimate opportunities to track the dynamics of all the characteristics of a broadband THz field in spatial, temporal, spectral, and angular coordinates [50] during its interference [18,19,21] and propagation, both in free space [9,12,17,22], through designed optical elements [51], obstacles [13,20], and investigated objects [8,10,11,16]. THz wavefront characterization with subsequent compensation through adaptive optics also serves as a compelling use case [52].…”