This PDF file contains the front matter associated with SPIE Proceedings Volume 11265 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

We present two single-shot experiments devoted to the study of noise-induced modulation instability (MI) in optical fibers. The first one, performed in a recirculating fiber loop, enables the first observation of the space-time dynamics of MI. The second one uses a heterodyne version of time microscope (SEAHORSE) that enables the single-shot observation of the phase and of the amplitude of the nonlinear random waves. Our SEAHORSE has a subpicosecond resolution and allows observation within a window of observation of 160ps. Our observations provide new experimental insights into the fundamental problem of spontaneous MI.

Non-classical correlated twin beams can be generated through the modulational instability in a hollow-core photonic crystal fibre filled with a noble gas. Since the gain is provided by a monatomic gas, the influence of Raman effect, which is typical for fibre-based sources of entangled photons, is avoided. Additionally, the gas pressure together with the frequency chirp of the input pump pulse allow continuous tuning of the number of frequency modes of the twin beams. We combine spectral interferometry and single-shot measurement to retrieve the phase of the noise-driven generated sidebands.

We will review our recent work in real-time measurements of nonlinear instabilities including the use machine learning, as well as the observation of a range of instability processes in novel dissipative systems such as the soliton-similariton laser.

Chimera states -- named after the mythical beast with a lion's head, a goat's body, and a dragon's tail -- correspond to spatiotemporal patterns characterised by the stable coexistence of coherent and incoherent domains. Here we report on experimental observations of chimera-like states in a continuous system subject to local coupling, namely a passive Kerr nonlinear ring resonator. We show that chimera-like states can be individually addressed in our system, i.e., turned on and off at will, and we explore their dynamics. Our experimental findings are in good agreement with numerical simulations based on the celebrated Lugiato-Lefever equation.

Microresonator combs have revolutionized the field of frequency metrology, replacing bulky mode-locked laser setups with chip-scale devices. While these novel comb sources have demonstrated their usefulness in numerous applications the exact nature of the mode-locking process in these devices appears to be not fully understood as it is commonly believed that synchronization between laser modes can only be achieved in the presence of an effective saturable absorber inside cavity. In the absence of saturable absorption, one would therefore expect that soliton solutions of the Haus master equation are not unconditionally stable against residual third-order dispersion. Consequently, deviations from a perfect equidistance may arise. Here we show that four-wave mixing processes can, to some extent, take over the role of saturable absorption and lead to a synchronization of modes. Within a certain range of dispersions, stable soliton solutions can be found not only in the anomalous dispersion regime, but also for zero, normal, or third-order dispersion. However, if the soliton conditions are not exactly matched, breather solutions form, and the resulting combs show deviations from equidistance.

An all-fiber time-stretched supercontinuum light source is presented. Time-stretching is obtained by dispersing the light in a specially designed highly dispersive fiber with a wide transmission bandwidth. The light source is based on a polarization-maintaining, self-starting femtosecond oscillator with repetition rate in the 1-10 MHz range. The supercontinuum stretches from 950 – 1700 nm and exhibits a high level of stability – both in terms of amplitude and repetition rate. The stretched light source is contained in a box with dimensions 25x25x5 cm³ with a single mode output fiber, making it suitable for a wide range of spectroscopy applications and swept source OCT.

In this paper, we will discuss the properties of long cavity frequency sweeping lasers and demonstrate various scenarios of coherence deterioration in such lasers. The long cavity lasers are known to demonstrate a rich variety of dynamical regimes including the formation of localised structures and transition to turbulence. The interest to frequency sweeping long cavity lasers has recently increased due to their application for imaging and sensing. For these applications, the stability of the laser is an important parameter as it directly influences its coherence and therefore, the quality of the obtained images.¹ Our laser consists of a fiber based ring cavity resonator including a semiconductor optical amplifier as a gain medium and a Fabry-Perot tunable filter. Experimentally, we considered different laser configurations which has allowed us to study the influence of the cavity length, frequency sweeping speed and the detuning. We considered the dynamical regimes of the laser operating at a static (fixed output frequency) and quasi { static regimes. The study shows that the laser can be stable or unstable and demonstrate localised structures stable over multiple roundtrips. We also show the connection of the dynamics observed in the static, quasi-static and synchronisation regimes of long cavity lasers. Numerically, we used a model based on a system of delayed differential equations. The numerical simulation showed excellent agreement with the experimental data. We also show the formation of dark pulses, both periodic and nonperiodic, and showed that they are closely connected to Nozaki-Bekki holes previously predicted in the complex Ginzburg-Landau equation.

Efficient frequency conversion is crucial for interfacing photons with a variety of quantum systems ranging from matter qubits (color centers, quantum dots, atoms), optical fibers, detectors, that often operate at widely different wavelengths. Frequency conversion is also a resource to process quantum information.^{1, 2} Parametric processes such as sum frequency generation (SFG) and Bragg scattering four wave mixing (BS-FWM) offer a good versatility for such frequency conversion. It is well understood that those nonlinear processes have to be strong enough and satisfy phase matching to achieve a high conversion efficiency. While it is enough to consider those two aspects for moderate conversion efficiency up to 50%, the analysis is a bit more complicated when targeting efficiencies closely approaching unity. We are reviewing the pitfall that must be avoided to indeed reach near unity frequency transduction.

Streaked visible spectroscopy is well established in dynamic compression research. Infrared measurements remain problematic, however, due to the diminishing sensitivity of streak camera photocathodes beyond 800 nm. Time-stretch techniques offer an alternative method for probing infrared features during single-event experiments. This paper discusses the development of a time-stretch spectroscopy diagnostic using dispersed supercontinuum laser pulses. The technique is applied to near-infrared measurements of liquid water during multiple shock compression.

This Conference Presentation, “Compressed Ultrafast Spectral Temporal (CUST) photography” was recorded at Photonics West LASE 2020, held in San Francisco, California, United States of America.

Temporal imaging system have enabled imaging of ultrafast phenomena with high temporal resolution different ultrafast phenomena. Specifically, time-lenses which are based on nonlinear interaction of four-wave mixing have a wide field of view together with high F-number. These offers temporal imaging system with large magnifications in the time-domain. However, when considering a time-lens based on four-wave mixing interaction, the input signal must be synchronized to the pump wave which makes it challenging for measuring any ultrafast phenomena with unknown time-of-arrival. Therefore, we developed a temporal imaging system which does not require this synchronization between a signal and a pump wave. This is done by generating time-lenses with high repetitionrate. Therefore, any input signal will interact with one of the time-lenses and it will be imaged in time with high probability. In this proceeding, we demonstrate how our temporal scheme is able to measure with high temporal resolution the start-up dynamics of pulsation in a fiber laser.

Time-lenses were developed rapidly over the last year. They enable measurements of ultrafast signals which were not measured before with limited electronics detectors. Time-lens enable to image ultrafast signals from sub picosecond time-scales to nanosecond time-scale while preserving the intensity, phase and state of polarization. However, most time-lenses are focus only on the time-domain and ignore the spatial domain. This hinder many ultrafast phenomena which combine the dynamics in time and space together. In this proceeding, we demonstrate the measured results of the mode splitter which is a crucial device for achieving a time-lens which combines time and space.

We demonstrate path-integrated simultaneous concentration measurements of water, methane and ethane, measuring spectra across the 3.1–3.5-μm range using 0.05 cm^-1 resolution Fourier-transform spectroscopy in-line with an ultrafast optical parametric oscillator and a simple, non-compliant target. Illumination spectra were extracted from a fitting procedure which simultaneously minimized the rms error between the experimental spectrum and a synthetic spectrum calculated from the envelope and a fitted mixture of PNNL or HITRAN absorbance data for water, methane and ethane. Simultaneous methane, ethane and water measurement at 30-m range were initially performed. Indoor measurements launched light from the OPO through a 20-cm-long gas cell containing a 1.5±0.15% ethane-in-air mixture. Light was reflected from a rough Al-foil target. Best-fit concentrations were determined to be 1.15% (water), 1860 ppb (methane) and 1.37 % (ethane). The methane background value is consistent with reported ambient levels. Respective water and ethane values were consistent with the ambient relative humidity. The second experiment demonstrated real-time methane emission measurement at 70-m range. A 2% methane:air mix was released for 100 seconds at a rate of 103 μgs^-1 at a distance of 65 m from the OPO. The signal was recorded from a simple target of rough aluminum foil situated 70 m from the OPO, with the beam passing near the emission point. This work demonstrates our ability to extract concentration data from a single spectrum with no need for averaging, which provides a real-time and quantitative monitoring capability.