We demonstrate a figure-of-9 all-fiber thulium-doped laser (TDFL) that generates 560 fs long pulses at 1948 nm wavelength. In order to achieve self-starting passive mode-locking, we utilize an in-fiber Faraday rotator to induce a nonreciprocal phase shift. To the best of our knowledge, this is the first all-fiber TDFL that combines an artificial saturable absorber (SA) with a chirped fiber Bragg grating (CFBG) as a wavelength-selective reflector. This cavity design is an excellent candidate to pump nonlinear processes such as supercontinuum and frequency comb generation since it does not require any SA material that degrades over time for mode-locking and could be made wavelength-tuneable via the CFBG.

We report the first, to our knowledge, observation of the nonlinear phenomenon known as modulation instability (MI) in a coherently driven fiber resonator pumped at 1972 nm. To compensate for the very high losses in this spectral region, we have integrated a thulium-doped fiber amplifier inside the cavity. Lower losses allow a lower MI threshold, leading to the observation of this phenomenon at a moderate input power. The results align closely with the numerical simulations of the system. Our study shows that active compensation of loss can be implemented in the 2 mu m wavelength range to construct fiber ring cavities with high finesse. It paves the way to the observation of more complex nonlinear effects optical frequency comb through cavity soliton generation. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

We demonstrate a polarization-maintaining passively mode-locked thulium-doped fibre laser that can operate at two different repetition rates (dual-comb) simultaneously.Based on the presented approach, we observe beat notes with a free spectral range of 1.97 kHz and aim to realize a free-running dual-comb source in the 2 µm band.

We report a stable, robust, and compact passively mode-locked thulium-doped fiber laser that can be wavelength-stabilized between 1958 and 2008 nm using the appropriate chirped fiber Bragg grating as a wavelength-selective element.

We demonstrate operation of a tunable mode-locked thulium-doped fiber laser, based on a wavelength-selective chirped fiber Bragg grating (CFBG). By applying strain to the CFBG, we shift its reflection band and can thereby tune the emission-wavelength of the fiber laser between 2022 nm and 2042 nm. We obtain a pulse train at 9.4 MHz repetition rate and a pulse duration between 9.0 and 12.8 ps. To the best of our knowledge, we report the first tunable mode-locked thulium-doped fiber laser using a tunable CFBG as wavelength-selective element.

We demonstrate an electro-optic polarisation converter for 1550nm at cryo genic temperatures in titanium in-diffused lithium niobate waveguides. The switching voltage increases, the modulation depth remains unchanged, and we show operation up to 25 MHz.

We demonstrate type-II SHG in fiber-coupled periodically-poled lithium niobate waveguides down to 4.4 K. This is the lowest temperature SHG experiment in an integrated photonic circuit, which is also compatible with other low temperature photonic technologies.

Superconducting detectors are now well-established tools for low-light optics, and in particular quantum optics, boasting high-efficiency, fast response and low noise. Similarly, lithium niobate is an important platform for integrated optics given its high second-order nonlinearity, used for high-speed electro-optic modulation and polarization conversion, as well as frequency conversion and sources of quantum light. Combining these technologies addresses the requirements for a single platform capable of generating, manipulating and measuring quantum light in many degrees of freedom, in a compact and potentially scalable manner. We will report on progress integrating tungsten transition-edge sensors (TESs) and amorphous tungsten silicide superconducting nanowire single-photon detectors (SNSPDs) on titanium in-diffused lithium niobate waveguides. The travelling-wave design couples the evanescent field from the waveguides into the superconducting absorber. We will report on simulations and measurements of the absorption, which we can characterize at room temperature prior to cooling down the devices. Independently, we show how the detectors respond to flood illumination, normally incident on the devices, demonstrating their functionality.