README: This document describes how to make use of the data used to produce the content of the manuscript, according to the open access regulations enforced by the funder(s).

CREATOR: Eugenio Di Gaetano (Eugenio.DiGaetano@glasgow.ac.uk)

IDENTIFIER: 

TITLE: Sub-MHz linewidth 780.24 nm distributed feedback laser for 87Rb applications

JOURNAL: Optics Letters

AUTHORS: Eugenio Di Gaetano1 , Scott Watson1, Euan McBrearty1, Marc Sorel1 and Douglas Paul1
1 University of Glasgow, James Watt School of Engineering, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, U.K.

DATES: project started December 2019, project end November 2022, data released May 2020

SUBJECT: Pictures of the simulated band structure, refractive index, vertical mode profile with and without the mode expander layer. Pictures of the simulated modal confinement in the QWs and propagation losses. SEM picture of a sidewall Bragg grating, used for device fabrication. Light-Intensity-Voltage (LIV) characteristic for the laser device, cooled at the temperature of 20C. The spectra of the laser device for different injected currents and cooled at the temperature of 20C. RF spectrum of the laser signal beaten with a reference narrow-linewidth laser. The DFB spectrum below the injection current threshold to calculate the kappa from the Bragg stopband.

FUNDERS: This work was supported by the U.K. EPSRC projects EEP/M013294/1, EP/N003225/1 and EP/T001046/1.

RIGHTS: University of Glasgow

METHODOLOGY: A Newport combo, thermoelectrical controller (TEC) and current driver, was employed to supply the laser device. The positive contact was biased through a micromanipulator with a conductive tip while the metallised sample back was used as negative contact. The sample back was also used as a heatsink, it was in contact with a Peltier cell which maintained a constant temperature of 20C by thermocouple feedback. The power was collected through a large area photodiode and recorded by a Newport power meter from the anti-reflect coated facet of the laser device while the current was injected through the current driver.
All the reported spectra were recorded by an Advantest optical spectrum analyser (OSA) with 0.01 nm resolution. The laser device's emitted light was collected with a single mode lensed fibre and guided to the OSA input. For the stopband measurement, a 2mm-long lambda/4-shifted DFB laser, which has a Bragg grating configuration equivalent to the laser device described in the manuscript, was electrically pumped at 195 mA, i.e. below the current threshold, and the stopband was measured to be approximately 0.14 nm around the Bragg peak at 777.75 nm. 
The RF beat signal was performed by beating a reference commercial Ti:Sapph laser, with a nominal linewidth of 50 kHz, with the laser device. The laser device output was collected with a single mode lensed fibre toward one of the ports of a 50%/50% fibre coupler while the light from the reference Ti:sapph laser was inserted in the second port of the fibre coupler. The mixed signal was beaten on a 10 GHz fast photodiode whose RF output was magnified by a 20dB-RF amplifier and, then, resolved by a RF spectrum analyser.

DATA: The data is provided in tab delimited text files.

USE: Any use of the data is subject to a Creative Commons license (CC BY 4.0) and the Optics Letter paper which first published the data should be cited. Five of the six figures are also provided in MatLab format.