The work performed in MILAS was divided into 5 work packages. The following was performed and achieved within each work package:
Work Package 1: Project Management & dissemination
Task 1.1 Project management, coordination and reporting
No challenges or delays were found between the coordination of the planned activities and the work carried out by the IA. All milestones have been accomplished within the project.
Task 1.2 Recruitment
The recruitment process started at the end of March 2017 and ended on May 1st, 2017. Interviews were carried out during May/June, and the candidate was selected in July 2017. The innovation associate started as scheduled, on September 1st, 2017.
Task 1.3 Risk management and contingency planning
No contingency planning or risk management was needed in the project.
Task 1.4 Dissemination
MILAS project resulted in two contributions to photonics conferences, SPIE Photonics West 2018 in San Francisco, and CLEO San Jose, 2018. At SPIE Photonic West, Norlase presented for the first time a Watt-level yellow laser system . The Innovation Associate participated in the characterization of this laser system and in preparing the manuscript. At CLEO San José, the demonstration of the first Watt-level pulses by dephasing modulation was presented by our CEO . Additionally, a scientific article entitled “2.7 W diffraction-limited yellow lasers by efficient frequency doubling of high-brightness tapered diode lasers” was submitted by the IA as the first author to the Elsevier journal “Optics and communications”.
Work package 2: Training
Task 2.1. In-house training
Two workshops were held at Norlase headquarters. The first one was focused on good-practices at Norlase labs, an introduction to the lab equipment and laser safety precautions. The second one introduced the IA to regulatory issues for medical products using lasers and provided a general overview of quality management.
Task 2.2 Short-terms stays
Two short terms stays were planned at research institutions relevant for the IA. One was completed within the project period, the second was scheduled after the project period.
Task 2.3 Core training events
The IA attended four seminars organized by the European Commission.
Work package 3: Temporal dynamics and feedback sensitivity
Tasks 3.1 Theoretical considerations on laser dynamics
The IA reviewed the state of the art of the tapered diode lasers.
Tasks 3.2 Diagnostics: measurements and characterization
Several experimental techniques were used by the IA to identify and to gain awareness on the laser dynamics as well as on the feedback effects. This was also helpful in understanding how modulation by de-phasing could be attained. The main outcome of this task is that Norlase incorporated in its assembly procedure a new way of determining whether the diode lasers are unstable after collimating the infrared beam.
Work package 4: New laser modulation scheme based on de-phased micro-pulsing
Tasks 4.1 Millisecond pulsing: mechanical shutter
Microsecond pulsing was demonstrated by using a mechanical shutter (NMlaser, LST200SLP). A customized shutter with an aperture larger than the offered in the NMlaser catalogue was required.
Tasks 4.2 Microsecond pulsing: current modulation de-phasing
De-phasing modulation was tested by driving the currents of two diode lasers of 4 and 6-mm long in different crystal lengths: 10, 40 and 80 mm (two-cascaded crystals).
Task 5.1Design select and purchase components.
The breadboard prototype (see Figure 1) was formed by a Norlase laser system, a fiber coupling system, and a mechanical shutter. The mechanical shutter was placed in the beam path before the light was coupled into the fiber (not shown in Figure 1). The breadboard also included custom-made electronics to drive the shutter.
Task 5.2 Construct breadboard prototype test breadboard prototype.
The tests carried out using the mechanical shutter and the electronics showed a stable operation of the shutter. In this case, the generation of the microsecond pulses is usually limited by the shutter lifetime, in the order of billions of counts. On the contrary, the microsecond pulsing is limited by the diode lifetime whenever the driving conditions and temperature setting remain unchanged.
