Enhanced signal coupling into periodically poled lithium niobate with microlens arrays

Abstract

The return signal frequency of an eye-safe ladar system is upconverted from the infrared to the visible through sum-frequency generation by incorporation of periodically poled LiNbO3 into the receiver. A quantitative analysis of the angular acceptance and the quantum efficiency is then presented for a single macroscopic receiver optic and a multiaperture microlens array. Comparing both results, a 6x increase in the receiver field of regard and an 18% increase in beam coupling were realized for the microlens design over the macroscopic system.

Inverted-conical light guide for crosstalk reduction in tightly-packed scintillator matrix and MAPMT assembly

“…Since the sample light guide utilized consecutive structure of the conical channels, one might think of the MLA as a similar comparison (Fig. 6) [26][27][28]. Indeed MLA has been demonstrated to have the ability of focusing the light and enhancing the image quality, and it has been widely applied to delicate optical products.…”

High-sensitivity 3 to 5 micron PPLN LADAR wavelength converter system

“…In this work we do not yet address this issue, but point to other work such as that by Brewer et al who demonstrated image upconversion using a multi-lens array to overcome the acceptance angle issues. 4,5,6 The experimental setup is shown in Figure 1. 3 µm pulses of light to simulate the LIDAR returns were generated from a seeded optical parametric generator (OPG).…”

“…2,3,4,5 The advantage of this scheme is that much higher sensitivity detectors may be used, including photon counting detectors. Detection technology in the near infrared (NIR) and visible is a much more mature technology than the mid-IR, and detection systems can take advantage of well-developed telecommunications technology.…”