Pawel Kaczmarek

Controlling the 1 μm spontaneous emission in Er/Yb co-doped fiber amplifiers

In this paper we present our experimental studies on controlling the amplified spontaneous emission (ASE) from Yb(3+) ions in Er/Yb co-doped fiber amplifiers. We propose a new method of controlling the Yb-ASE by stimulating a laser emission at 1064 nm in the amplifier, by providing a positive 1 μm signal feedback loop. The results are discussed and compared to a conventional amplifier setup without 1 μm ASE control and to an amplifier with auxiliary 1064 nm seeding. We have shown, that applying a 1064 nm signal loop in an Er/Yb amplifier can increase the output power at 1550 nm and provide stable operation without parasitic lasing at 1 μm.

All-fiber Ho-doped mode-locked oscillator based on a graphene saturable absorber

In this Letter, we demonstrate a graphene mode-locked, all-fiber Ho-doped fiber laser generating 1.3 nJ energy pulses directly from the oscillator. The graphene used as a saturable absorber was obtained via chemical vapor deposition on copper substrate and immersed in a poly(methyl methacrylate) support. The laser generated ultrashort soliton pulses at 2080 nm with bandwidth up to 6.1 nm. The influence of the output coupling ratio and the SA modulation depth on the mode-locking performance was also investigated.

Cloud orchestration with SDN/OpenFlow in carrier transport networks

Software Defined Networking offers network programmability through open Application Programming Interfaces (API) and OpenFlow is the most prominent SDN protocol today. However, it is still quite immature and some concepts and features are missing for application in carrier transport networks. In this paper the authors will give an overview of current activities and latest results of the OFELIA project for OpenFlow enabled lambda switching in ROADM-based optical networks. Then the authors highlight required functionality and propose a system architecture to offer cloud orchestration services over multi-carrier and multi-technology transport networks.

High-Power Fiber-Based Femtosecond CPA System at 1560 nm

We demonstrate a fiber-based, high-power, high-repetition rate chirped pulse amplification system operating at 1560 nm. The system is seeded by a graphene mode-locked Er-doped fiber laser with 50 MHz repetition rate. The all-fiber amplifier chain consists of three stages, out of which the last stage utilizes a large-mode area Er 3+/Yb 3+ co-doped fiber. In order to reduce the complexity of the system, the pulses are temporally broadened in a segment of inverse dispersion fiber. After amplification, the pulses are compressed in a two reflection grating-based compressor. The system provides 835 fs-short pulses with 8.65 W of average power. The demonstrated system, except of the compressor, is designed in all-fiber technology, providing robustness, compactness and environmental stability.

WDM optocommunication technology used for multipoint fibre vibrometry

The multichannel WDM (Wavelength Division Multiplexing) technique inspired the concept of vibration measurements for many points of a vibrating object. The N-independent WDM separated 15XX nm fibre coupled laser diodes (used for optical fibre telecommunication) form coherent system of sources for multipoint measurement of vibrations according to the rule one wavelength - one point. The scattered light from the object coupled into the fibre, filtered coherently, after special signal processing, allows analysing amplitudes and phases of many vibrating points in real time. Some experiments and results of such system will be demonstrated.

Laser-fiber vibrometry/velocimetry using telecommunication devices

We presented the next step of our research connected with development of the vibrometry/velocimetry based on fiber into free space radiation and heterodyne detection of scattered light. Some experimental configurations utilizing erbium doped fiber amplifier (EDFA) are presented. We propose two solutions of optical interface between the fiber system and an object.

Study of a Social Robot's Appearance Using Interviews and a Mobile Eye-Tracking Device

During interaction with a social robot, its appearance is a key factor. This paper presents the use of methods more widely utilized in market research in order to verify the design of social robot FLASH during a short-term interaction. The proposed approach relies on in-depth interviews with the participants as well as data from a mobile device which allows the tracking of ones gaze.

Design for a Robotic Companion

We can learn from the history of robotics that robots are getting closer to humans, both in the physical as well as in the social sense. The development line of robotics is marked with the triad: industrial — assistive — social robots, that leads from human–robot separation toward human–robot interaction. A social robot is a robot able to act autonomously and to interact with humans using social cues. A social robot that can assist a human for a longer period of time is called a robotic companion. This paper is devoted to the design and control issues of such a robotic companion, with reference to the robot FLASH designed at the Wroclaw University of Technology within the European project LIREC, and currently developed by the authors. Two HRI experiments with FLASH demonstrate the human attitude toward FLASH. A trial testing of the robots emotional system is described.

Double-Seeding of Er/Yb Co-Doped Fiber Amplifiers for Controlling of Yb-ASE

In this paper, we present our investigations on controlling the amplified spontaneous emission from Yb ions in erbium/ytterbium co-doped fiber amplifier by double-seeding of the amplifier with nominal (1.55 μm) and auxiliary (1 μm). The dependence of the amplifier output power on the auxiliary seed wavelength and input power is analyzed. The obtained results are discussed and compared to a conventional amplifier setup without auxiliary seed signal. Our studies show that introducing an auxiliary seed at proper wavelength from the Yb-band provides stable amplifier operation without parasitic lasing at 1 μm and can also increase output power of the nominal 1550 nm signal.

Recent development of WDM fiber vibrometry

For the last few years we were elaborating the laser-fiber vibrometer working at 1550 nm. Our main stress was directed towards different aspects of research: analysis of scattered light, efficient photodetection, optimisation of the fiber-free space interfaces and signal processing. As a consequence we proposed the idea of a multichannel fiber vibrometer based on well developed telecommunication technique – Wavelength Division Multiplexing (WDM). We present the results of a just finished project “Developing novel laser-fiber monitoring technologies to prevent environmental hazards from vibrating objects” where we have constructed a 4-channel WDM laser-fiber vibrometer.