Holistic Nanowire Laser Characterization as a Route to Optimal Design

Abstract

Nanowire lasers are sought for near‐field and on‐chip photonic applications as they provide integrable, coherent, and monochromatic radiation: the functional performance (threshold and wavelength) is dependent on both the opto‐electronic and crystallographic properties of each nanowire. However, scalable bottom‐up manufacturing techniques often suffer from inter‐nanowire variation, leading to differences in yield and performance between individual nanowires. Establishing the relationship between manufacturing controls, geometric and material properties, and the lasing performance is a crucial step toward optimisation; however, this is challenging to achieve due to the interdependance of such properties. Here, a high‐throughput correlative approach is presented to characterise over 5000 individual GaAsP/GaAs multiple quantum well nanowire lasers. Fitting the spontaneous emission provides the threshold carrier density, while coherence length measurements determine the end‐facet reflectivity. The performance is intrinsically related to the width of a single quantum well due to quantum confinement and bandfilling effects. Unexpectedly, there is no strong relationship between the properties of the lasing cavity and the threshold: instead the threshold is negatively correlated with the non‐radiative recombination lifetime of the carriers. This approach therefore provides an optimisation strategy that is not accessible through small‐scale studies.

Improving Quantum Well Tube Homogeneity Using Strained Nanowire Heterostructures

“…Measurement of the quantum efficiency (QE) of these structures is challenging due to differing slice thickness and dielectric environment due to the supporting resin matrix; however, similar structures show a high QE of 40%. 41 The median PL, across all measured structures, is 1546 −3…”

“…The ambipolar diffusion length in GaAs can reach twice the structure size of our samples; it is likely that emission will reflect inhomogeneity in emission sites rather than all sites present. Measurement of the quantum efficiency (QE) of these structures is challenging due to differing slice thickness and dielectric environment due to the supporting resin matrix; however, similar structures show a high QE of 40% …”

Bottom-up, Chip-Scale Engineering of Low Threshold, Multi-Quantum-Well Microring Lasers

“…Terminating the measurement in this manner enables the threshold to be determined for each microring, while dramatically increasing the speed of the measurements, and protecting each device from potential damage due to exposure to excessive fluence. The threshold fluence for the first lasing mode is determined by using a least-squares fitting routine applied to the integrated intensity of this peak: further details of the experiment and analysis can be found in ref 46. The spectral resolution of the setup is 1 nm; therefore, the lasing peaks detected in the high-throughput experiment are resolution-limited.…”

“…The automated lasing measurements on the microrings were performed using a homemade optical microscope that has been developed to perform rapid and simultaneous measurements of luminescence spectra and optical images. 46 The microrings were located using optical microscopy and visited sequentially for lasing study. They were excited at 633 nm using the ultrafast (subpicosecond) output from an optical parametric amplifier system.…”

Single-mode nanolasers based on FP-WGM hybrid cavity coupling

“…Semiconductor nanowires (NWs) are an emerging class of nanomaterials and have drawn significant attention in the recent era because of their potential for the nanoscale optoelectronic, photonic devices and circuits [1][2][3][4][5][6][7][8][9][10] with several advantages such as low power consumption [11][12][13], compact sizes [14,15], and low cost [16,17]. Semiconductor NW lasers are highly desirable for the next-generation coherent light sources owing to their wide application in various fields including optical communication [18][19][20][21], optical sensing [22][23][24] and integrated optics [25][26][27]. Acting as both the gain media and the resonant cavity [28], generally, a semiconductor NW-based nanolaser lases when the round-trip gain compensates for the round-trip loss in a microcavity supported by the end face reflection of the NW [5].…”