Embodiments of the present disclosure may relate to a digitized grating that may include a first unit cell that has a first period and a first length, where the first period includes a first grating element width and a first space between adjacent grating elements, and where the first length includes a number of first periods. The digitized grating may further include a second unit cell that has a second period and a second length, where the second period is different than the first period and includes a second grating element width and a second space between adjacent grating elements, and where the second length includes a number of second periods.

A tunable laser device includes a laser structure and a plurality of individually addressable, separated contact stripes disposed on the laser structure. The laser structure includes a substrate, an active portion disposed on the substrate, and a chirped distributed feedback (DFB) grating disposed on the active portion. The active portion includes at least top and bottom contact layers and a gain medium.

The present disclosure describes a microring OAM laser producing an optical vortex beam with an on-demand topological charge and vector polarization states. This is enabled through combined index and gain/loss modulations at an EP, which breaks the mirror symmetry in the lasing generation dynamics and facilitates unidirectional power oscillation.

Disclosed is a Vernier effect DBR laser that has uniform laser injection current pumping along the length of the laser. The laser can include one or more tuning elements, separate from the laser injection element, and these tuning elements can be used to control the temperature or modal refractive index of one or more sections of the laser. The refractive indices of each diffraction grating can be directly controlled by temperature changes, electro optic effects, or other means through the one or more tuning elements. With direct control of the temperature and/or refractive indices of the diffraction gratings, the uniformly pumped Vernier effect DBR laser can be capable of a wider tuning range. Additionally, uniform pumping of the laser through a single electrode can reduce or eliminate interfacial reflections caused by, for example, gaps between metal contacts atop the laser ridge, which can minimize multi-mode operation and mode hopping.

A tunable laser has a first mirror, a second mirror, a gain medium, and a directional coupler. The first mirror and the second mirror form an optical resonator. The gain medium and the directional coupler are, at least partially, in an optical path of the optical resonator. The first mirror and the second mirror comprise binary super gratings. Both the first mirror and the second mirror have high reflectivity. The directional coupler provides an output coupler for the tunable laser.

An optical grating comprising a refractive index with a periodic pattern that includes a base period ?.sub.0; a periodic sampling of the base period, with a first period ?.sub.1 and a first duty cycle p.sub.1, thereby defining a single-sampled grating (SSG); and a periodic sampling of the SSG, with a second period ?.sub.2 and a second duty cycle p.sub.2. The resulting dual-sampled grating (DSG) can have a reflection spectrum containing reflection peaks. If two DSGs having different reflection spectra share a common interface, a tunable optical filter can be produced, where electrical or heating means can cause a reflection peak of one spectrum to be shifted to coincide with a reflection peak of the other spectrum, thereby filtering the corresponding wavelength. By inserting between the two DSGs a gain medium and a phase-tuning medium, a laser source structure is realized. Either device can be produced by etching or stacking methods.

A semiconductor laser device having a diffraction grating is disclosed. The semiconductor laser device comprises a first diffraction grating provided on a substrate, a second diffraction grating continuous to one end of the first diffraction grating along an optical waveguide direction, and an active layer provided above the first diffraction grating. The second diffraction grating has a pitch 1.05 times or greater, or 0.95 times or smaller of the pitch of the first diffraction grating.

A method of characterizing a monolithic tunable mid-infrared laser including a heterogeneous quantum cascade active region together with a least first and a second tunable integrated distributed feedback gratings, the method including operating the laser while tuning the first grating through its full tuning range, while holding the reflectivity function of the second grating constant, then operating the laser while tuning the second grating through its full tuning range, while holding the reflectivity function of the first grating constant.