Jan Tarka

Passive synchronization of erbium and thulium doped fiber mode-locked lasers enhanced by common graphene saturable absorber

In this work we present for the first time, to the best of our knowledge, a passively synchronized thulium (Tm) and erbium (Er) doped fiber laser mode-locked by a common graphene saturable absorber (GSA). The laser consists of two ring resonators combined with a 90 cm long common fiber branch incorporating the saturable absorber (SA). Such laser generates optical solitons centered at 1558.5 nm and 1938 nm with pulse durations of 915 fs and 1.57 ps, respectively. Both laser loops were passively synchronized at repetition frequency of 20.5025 MHz by nonlinear interaction (cross phase modulation, XPM) in common fiber branch between generated pulses. The maximum cavity mismatch of the Er-laser in synchronization regime was 0.78 mm. The synchronization mechanism was also investigated. We demonstrate that the third order nonlinearities of graphene enhance the synchronization range. In our case the range was increased about 85%. The integrated RMS timing jitter between the synchronized pulses was 67 fs.

168 fs pulse generation from graphene-chitosan mode-locked fiber laser

We propose new graphene-chitosan solution as a saturable absorber for a mode-locked Erbium-doped fiber laser. We demonstrate stable, mode-locked operation with pulse as short as 168 fs, which are the shortest pulses generated from an Er-doped fiber laser with the use of graphene so far. Graphene-chitosan solution was obtained in soluble forms by the addition of the acetic acid. The ring laser is able to generate optical solitons centered at 1554 nm wavelength with 15.2 nm bandwidth and 63 MHz repetition rate.

Power Scaling of an All-PM Fiber Er-Doped Mode-Locked Laser Based on Graphene Saturable Absorber

This paper presents the study on power scaling of an all-polarization maintaining (PM) fiber mode-locked laser using the multilayer chemical vapor deposition graphene/poly(methyl methacrylate) composite as a saturable absorber by changing the coupling ratio of the laser output coupler. Pulses with the duration of 148 fs were generated using 10% output coupler, which are the shortest pulses obtained from mode-locked erbium doped fiber laser working in anomalous dispersion regime, additionally the highest average output power of 15.66 mW was achieved by applying 70% output coupler. All-PM fiber resonator configuration provides self-start and stable operation. To our knowledge, this is the first comprehensive study of power scaling of erbium doped fiber laser with graphene saturable absorber. Conducted experimental work is in very good agreement with numerical simulations.

Sb2Te3 topological insulator based saturable absorber for Er-doped mode-locked fiber lasers

We present an Er-doped fiber mode-locked laser based on an evanescent field interaction with the Sb2Te3 topological insulator. The saturable absorber (SA) consist of a bulk piece of Sb2Te3 material placed on the side-polished fiber in the presence of UV curable polymer. The measured SA optical parameters like: linear absorption, modulation depth and non-saturable loses were of 50%, 6% and 43%, respectively. The SA was spliced into the ring laser cavities characterized by the all-anomalous, all-normal and balanced dispersion. Such laser resonators allowed for optical solitons, dissipative solitons and Gaussian pulses generation with 3dB bandwidth of 8.5 nm, 37 nm and 17 nm, respectively.

Sensitive detection of carbon monoxide using a compact high power CW DFB-QCL based QEPAS sensor

Development of an ultra-sensitive, selective, and compact QEPAS-based CO sensor employing a high power CW DFB-QCL is reported. A minimum detectable concentration of 4ppbv was achieved for CO line (2169.2cm-1) using a 5sec data acquisition time.

2 µm ultrafast fiber laser modelocked by mechanically exfoliated Sb2Te3

We demonstrate the usage of a saturable absorber material - antimony telluride (Sb2Te3) for efficient mode-locking of a Thulium-doped fiber laser. The Sb2Te3 layers were obtained by mechanical exfoliation and transferred onto the fiber ferrule. The all-fiber laser was capable of generating optical solitons with the full width at half-maximum of 4.5 nm centered at 1945 nm, with 39.5 MHz repetition rate and more than 60 dB signal to noise ratio. The pulse energy of the generated 890 fs pulses was at the level of 30 pJ. Our experiment showed that Sb2Te3 saturable absorbers are suitable for the operation in 2 μm bandwidth.

All-normal dispersion Yb-doped fiber laser mode-locked by Sb2Te3 topological insulator

In this paper we demonstrate a preliminary work done on employing antimony telluride (Sb2Te3) topological insulator as a saturable absorber for Yb-doped fiber lasers. The material was deposited onto a side-polished fiber by means of a pulsed magnetron sputtering technique. Fabricated absorber was implemented in an all-normal dispersion cavity and allowed for self-starting dissipative soliton generation. The laser emitted stable pulse train at a repetition rate of 17.07 MHz with 4.25 nm broad output spectrum centered around 1039.4 nm. Average output power amounted to 0.54 mW with 32 pJ pulse energy.

Compact, all-PM fiber-CPA system based on a chirped volume Bragg grating

We demonstrate the chirped pulse amplification (CPA) of ultrashort pulses in a compact setup utilizing a chirped volume Bragg grating (CVBG) at 1560 nm wavelength. The system comprises a seed laser, dual-stage fiber amplifier and one CVBG, which is used as a stretcher and compressor simultaneously. The pulses from the low-power oscillator were amplified to 1 W of average power at a 50 MHz repetition rate with a pulse duration of 2.44 ps. The setup utilizes only polarization maintaining (PM) fibers and components, which ensures excellent stability and immunity to external disturbances. The output beam is linearly polarized with excellent geometrical quality (M 2 parameter close to 1). The usage of CVBG instead of classical grating-based stretchers and compressors allows the reduction of the complexity of the CPA system and minimizes its footprint. Such a simple and compact setup might be used as a pump source for nonlinear frequency conversion or mid-infrared supercontinuum generation.

Mid-infrared Laser Based Gas Sensor Technologies for Environmental Monitoring, Medical Diagnostics, Industrial and Security Applications

Recent advances in the development of compact sensors based on mid-infrared continuous wave (CW), thermoelectrically cooled (TEC) and room temperature operated quantum cascade lasers (QCLs) for the detection, quantification and monitoring of trace gas species and their applications in environmental and industrial process analysis will be reported. These sensors employ a 2f wavelength modulation (WM) technique based on quartz enhanced photoacoustic spectroscopy (QEPAS) that achieves detection sensitivity at the ppbv and sub ppbv concentration levels. The merits of QEPAS include an ultra-compact, rugged sensing module, with wide dynamic range and immunity to environmental acoustic noise. QCLs are convenient QEPAS excitation sources that permit the targeting of strong fundamental rotational-vibrational transitions which are one to two orders of magnitude more intense in the mid-infrared than overtone transitions in the near infrared spectral region.

Graphene oxide paper as a saturable absorber for Er-doped fiber laser

In this work, femtosecond pulse generation in Er-doped fiber laser using graphene oxide (GO) paper based saturable absorber (SA) is presented. The article includes the characterization of optical properties of prepared SA material and detailed description of the laser performance. Stable mode-locking operation was achieved, with 515 fs soliton pulses centered at 1559 nm. The GO paper SA is characterized by 5.4% modulation depth and 155 MW/cm2 of saturation intensity. The nearly wavelength-independent linear absorption combined with straightforward fabrication process make it a suitable material for application as a SA in low-power mode-locked fiber lasers operating in various spectral ranges.