Southeast Tech

We phase-lock a frequency comb based on a few-cycle Cr:ZnS laser oscillator to its narrow-linewidth optical pump, creating a set of mutually coherent optical frequency combs that span from the visible to the long-wave IR.

Ultrafast lasers based on Cr2+-doped II-VI semiconductors provide a convenient way to generate optical frequency combs in a broad spectral range. We will give an overview of Cr2+- based femtosecond sources and their applications in dual-comb spectroscopy.

Optical frequency combs based on mode-locked Cr:ZnS lasers uniquely combine multi-octave bandwidth, high brightness, and compactness. We demonstrate spectroscopy with dual Cr:ZnS combs accessing 800,000 comb teeth spanning 2000 cm–1 in the middle-IR.

In a dynamic framework, we study pricing strategies in two-sided markets while considering users' expectations. The results show that in the steady-state equilibrium, except for the indirect network effects, the growth rates and users' beliefs may also cause skewed pricing. In non-equilibrium, we find that in the early period, the platform may delay the entrance of users on one side and attract only users on the other side if the costs of attracting a large user base on this side are large. Besides, when the weight coefficients of the conjectured numbers that depend on users' beliefs are high, the optimal price trajectories increase rapidly in the period when the numbers of users are low and then converge to low equilibrium prices.

This joint issue of Optics Express and Optical Materials Express features 17 state-of-the art articles written by authors who participated in the international conference Advanced Solid-State Lasers held in Vienna, Austria, from September 29 to October 3, 2019. This introduction provides a summary of these articles that cover numerous areas of solid-state lasers from materials research to sources and from design to experimental demonstration.

We demonstrate the generation of a supercontinuum spanning more than 1.5 octaves over the 1.2–3.7 µm range in a silicon nitride waveguide using sub-40-fs pulses at 2.35 µm generated by a 75 MHz Kerr-lens mode-locked Cr:ZnS laser.

We reveal energy transfer between chromium-iron and cobalt-iron ions in co-doped II-VI chalcogenide laser materials with a rate faster than 300 ns, which is attractive for development of effective mid-IR lasers operating over 3.5-6.0 µm.

The problem of optimal resource allocation in wireless networks usually involves scheduling of the network independent sets (ISs), of which the number increases exponentially in the network scale. To deal with such large-scale optimization problems, traditional approaches often resort to some heuristics or iterative algorithms for obtaining a relatively small set of ISs to solve the problems, but at the cost of suboptimality or long convergence time. In this paper, we consider wireless network resource allocation in dynamic flow environments, aiming at maximizing the network capacity. We propose a learning-based approach to find ISs based on the dynamic flow demands. Specifically, instead of searching for individual ISs, we propose to learn groups of ISs by using a deep belief network (DBN). We present detailed design of the DBN-based learning method including details in the offline training and online running phases. Simulation results demonstrate that our DBN-based method outperforms existing ones in terms of achieved network capacity and computation time.

High-power (0.5 W) mid-IR output suitable for ultra-broadband frequency comb generation was produced in a subharmonic GaAs optical parametric oscillator that was synchronously pumped by a compact 0.9 GHz, 6 W femtosecond Cr:ZnS (2.35μm) MOPA.