Observation of Boyer-Wolf Gaussian modes.

Stable laser resonators support three fundamental families of transverse modes: the Hermite, Laguerre, and Ince Gaussian modes. These modes are crucial for understanding complex resonators, beam propagation, and structured light. We experimentally observe a new family of fundamental laser modes in stable resonators: Boyer-Wolf Gaussian modes.

Energy scaling of a narrowband, periodically poled LiNbO, nanosecond, nonresonant optical parametric oscillator.

We demonstrate that 3-mm-thick, periodically poled enables energy scaling of a nonresonant optical parametric oscillator operated in the narrowband mode with a volume Bragg grating at the signal wavelength. Utilizing the full available pump power at 1064 nm, we obtained maximum average powers of 2.25 and 2.

Narrowband, intracavity-pumped, type-II BaGaGeSe optical parametric oscillator.

We present a tunable (6.62-11.34 µm), singly-resonant, cascade optical parametric oscillator with intracavity pumping of BaGaGeSe in the second stage and spectral narrowing realized by a Volume Bragg Grating acting on the signal wave of the first stage which serves as a pump for the second stage.

Compact dual-band spectral analysis via multiplexed rotated chirped volume Bragg gratings.

Chirped Bragg volume gratings (CBGs) offer a useful alternative for spectral analysis, but increasing the bandwidth necessitates increasing the device area. In contrast, recently developed rotated CBGs (r-CBGs), in which the Bragg structure is rotated by 45° with respect to the device facets, require increasing only the device length to extend the bandwidth, in addition to the convenience of resolving the spectrum at normal incidence. Here, we multiplex r-CBGs in the same device to enable spectral analysis in two independent spectral windows without increasing the system volume.

Ultra-compact synthesis of space-time wave packets.

Space-time wave packets (STWPs) are pulsed fields in which a strictly prescribed association between the spatial and temporal frequencies yields surprising and useful behavior. However, STWPs to date have been synthesized using bulky free-space optical systems that require precise alignment. We describe a compact system that makes use of a novel optical component: a chirped volume Bragg grating that is rotated by 45° with respect to the plane-parallel device facets.

Rotated chirped volume Bragg gratings for compact spectral analysis.

We introduce a new, to the best of our knowledge, optical component-a rotated chirped volume Bragg grating (r-CBG)-that spatially resolves the spectrum of a normally incident light beam in a compact footprint and without the need for subsequent free-space propagation or collimation. Unlike conventional chirped volume Bragg gratings in which both the length and width of the device must be increased to increase the bandwidth, by rotating the Bragg structure we sever the link between the length and width of a r-CBG, leading to a significantly reduced device footprint for the same bandwidth. We fabricate and characterize such a device in multiple spectral windows, we study its spectral resolution, and confirm that a pair of cascaded r-CBGs can resolve and then recombine the spectrum.

Full-color eye-box expansion via holographic volume gratings recorded in photo-thermo-refractive glass.

Conventional head-up displays (HUDs) suffer from a limited exit pupil and a lack of compactness mainly due to the use of bulky optics. HUDs need a high-quality image with a large field of view (FOV) in small packaging to gain commercial acceptability. Holographic HUDs are phase-only devices that allow vision correction and focus adjustment while having a wide FOV.

Intracavity spatial mode conversion by holographic phase masks.

Past beam-shaping techniques, developed to transform a Gaussian beam into other waveforms, rely on a wide selection of available tools ranging from physical apertures, diffractive optical elements, phase masks, free-form optics to spatial light modulators. However, these devices - whether active or passive - do not address the underlying monochromatic nature of their embedded phase profiles, while being hampered by the complex, high-cost manufacturing process and a restrictive laser-induced damage threshold. Recently, a new type of passive phase devices for beam transformation - referred to as holographic phase masks (HPMs), was developed to address these critical shortcomings.

Wavefront shaping optical elements recorded in photo-thermo-refractive glass.

The paper presents an overview of the benefits of recording phase masks into the bulk of photo-thermo-refractive glass. We demonstrate that both binary and gray-scale phase masks can be encoded into the medium, and that such masks can be used for mode conversion and beam shaping with near-theoretical efficiency. We further demonstrate that by encoding the phase mask profile into a transmitting volume Bragg grating, it is possible to create tunable and achromatic phase masks without requiring a complex phase pattern.

Passively Q switched dual channel Tm:YLF laser by intracavity spectral beam combination with volume Bragg gratings.

A novel dual channel Tm:YLF laser system was developed where two degenerate laser cavities were coupled by spectrally beam combining their emission and by implementing a common output coupler. Under continuous wave running conditions, each channel's slope efficiency was greater than 45% and the maximum combined output power was 11 W. Passive Q-switching was achieved using an 80%, Cr:ZnSe saturable absorber.

Ultralow Dispersion Multicomponent Thin-Film Chalcogenide Glass for Broadband Gradient-Index Optics.

A novel photothermal process to spatially modulate the concentration of sub-wavelength, high-index nanocrystals in a multicomponent Ge-As-Pb-Se chalcogenide glass thin film resulting in an optically functional infrared grating is demonstrated. The process results in the formation of an optical nanocomposite possessing ultralow dispersion over unprecedented bandwidth. The spatially tailored index and dispersion modification enables creation of arbitrary refractive index gradients.

An ultra-narrow linewidth solution-processed organic laser.

Optically pumped lasers based on solution-processed thin-film gain media have recently emerged as low-cost, broadly tunable, and versatile active photonics components that can fit any substrate and are useful for, e.g., chemo- or biosensing or visible spectroscopy.

High-contrast filtering by multipass diffraction between paired volume Bragg gratings.

High-contrast filtering via multiple reflections between matched volume Bragg gratings (VBGs) is demonstrated. The use of multiple reflections serves to increase the suppression ratio of the out-of-band spectral content such that contributions of grating sidelobes can be mitigated. The result is a device that retains spectral and angular selectivity and diffracts light into a single order with high efficiency but reshapes the spectral/angular response to achieve higher signal-to-noise ratios.

Saturation of multiplexed volume Bragg grating recording.

Recording of volume Bragg gratings (VBGs) in photo-thermo-refractive glass is limited to a maximum refractive index change about 0.002. We discuss various saturation curves and their influence on the amplitudes of recorded gratings.

Moiré volume Bragg grating filter with tunable bandwidth.

We propose a monolithic large-aperture narrowband optical filter based on a moiré volume Bragg grating formed by two sequentially recorded gratings with slightly different resonant wavelengths. Such recording creates a spatial modulation of refractive index with a slowly varying sinusoidal envelope. By cutting a specimen at a small angle, to a thickness of one-period of this envelope, the longitudinal envelope profile will shift from a sine profile to a cosine profile across the face of the device.

Stabilization system for holographic recording of volume Bragg gratings using a corner cube retroreflector.

Volume Bragg gratings serve an important role in laser development as devices that are able to manipulate both the wavelength and angular spectrum of light. A common method for producing gratings is holographic recording of a two collimated beam interference pattern in a photosensitive material. This process requires stability of the recording system at a level of a fraction of the recording wavelength.

Scaling the spectral beam combining channels in a multiplexed volume Bragg grating.

In order to generate high power laser radiation it is often necessary to combine multiple lasers into a single beam. The recent advances in high power spectral beam combining using multiplexed volume Bragg gratings recorded in photo-thermo-refractive glass are presented. The focus is on using multiple gratings recorded within the same volume to lower the complexity of the combining system.

Effect of aberrations in a holographic system on reflecting volume Bragg gratings.

The effect of aberrations in the recording beams of a holographic setup is discussed regarding the deterioration of properties of a reflecting volume Bragg grating. Imperfect recording beams result in a spatially varying grating vector, which causes broadening, asymmetry, and washed out side lobes in the reflection spectrum as well as a corresponding reduction in peak diffraction efficiency. These effects are more significant for gratings with narrower spectral widths.

Electric-field-driven nano-oxidation trimming of silicon microrings and interferometers.

Nanoscale disorder results in severe spectral misalignment of silicon microring resonators and Mach-Zehnder interferometers. We correct for such effects using electric-field-induced waveguide nano-oxidation, demonstrating a tuning wavelength range of several nanometers and 0.002 nm resolution without line shape degradation.

Quantitative infrared imaging of silicon-on-insulator microring resonators.

There is considerable research activity in multiresonator optical circuits in silicon photonics, e.g., for higher-order filters, advanced modulation format coding/decoding, or coupled-resonator optical waveguide delay lines.