The disclosure relates in some aspects to providing miniature power-efficient agile photonic generators of microwave waveforms. Illustrative examples use chip lasers integrated in close thermal proximity with one another to provide a miniature microwave arbitrary waveform generator (AWG). Due to the small size of the lasers and the close integration, common ambient fluctuations from the environment or other sources can be efficiently reduced, yielding improved spectral purity of generated radio-frequency (RF) signals. Tight physical integration also permits a small device footprint with minimal acceleration sensitivity. The lasers may be locked to cavities or other resonators to allow efficient decoupling of the frequency and amplitude modulation of the lasers to provide flexibility to the waveform generator. Exemplary devices described herein can produce frequency chirped signals for radar applications. The frequency chirp may be linear and/or nonlinear. Tuning methods are also described herein.

Narrow-optical linewidth laser generation devices and methods for generating a narrow-optical linewidth laser beam are provided. One narrow-optical linewidth laser generation devie includes a single-wavelength mirror or multiwavelength mirror (for comb lasers) formed from one or more optical ring resonators coupled with an optical splitter. The optical splitter may in turn be coupled with a quantum dot optical amplifier (QDOA), itself coupled with a phase-tuner. The phase tuner may be further coupled with a broadband mirror. The narrow-optical linewidth laser beam is generated by using a long laser cavity and additionally by using an integrated optical feedback.

An optical filter includes a first loop mirror, a second loop mirror, a first waveguide optically coupled to the first loop mirror and the second loop mirror, and a first access waveguide. The first loop mirror includes a first loop waveguide and a first multiplexer/demultiplexer. The second loop mirror includes a second loop waveguide and a second multiplexer/demultiplexer. The first loop waveguide is optically coupled to the first multiplexer/demultiplexer. The second loop waveguide is optically coupled to the second multiplexer/demultiplexer. The first waveguide is optically coupled to the first multiplexer/demultiplexer and the second multiplexer/demultiplexer. The first access waveguide is optically coupled to the first waveguide.

A laser system for generating a narrow linewidth semiconductor light beam includes a substrate, a gain chip affixed on the substrate and configured to amplify light beam, and an optical feedback photonic chip affixed on the substrate, optically coupled to the gain chip, and configured to output light beam, which has a narrow linewidth around a resonant frequency of the optical feedback photonic chip, to the gain chip. The optical feedback photonic chip includes first and second optical gratings, a first multimode interferometer (MMI) and a second MMI optically coupled with a respective end of the first and second optical gratings, a third MMI configured to output two light beams to the first and second MMIs, respectively, through a respective waveguide. Based on receiving a respective one of the two light beams, the first MMI outputs two light beams to its respective end of the first and second optical gratings and the second MMI outputs two light beams to its respective end of the first and second optical gratings, the first and second optical gratings output second and third light beams, the second light beam, of which a linewidth is narrower than a linewidth of the third light beam, is directed to the third MMI, and an output port of the third MMI is configured to direct the second light beam to the gain chip.

An optical semiconductor device includes an active layer having a plurality of quantum dot layers. The plurality of quantum dot layers include: a first quantum dot layer doped with a p-type impurity; and a second quantum dot layer doped with an n-type impurity and having an emission wavelength different from that of the first quantum dot layer.

A spectroscopic laser sensor based on hybrid III-V/IV system-on-a-chip technology. The laser sensor is configured to either (i) be used with a fiber-optic probe connected to an intravenous/intra-arterial optical catheter for direct invasive blood analyte concentration level measurement or (ii) be used to measure blood analyte concentration level non-invasively through an optical interface attached, e.g., to the skin or fingernail bed of a human. The sensor includes a III-V gain-chip, e.g., an AlGaInAsSb/GaSb based gain-chip, and a photonic integrated circuit, with laser wavelength filtering, laser wavelength tuning, laser wavelength monitoring, laser signal monitoring and signal output sections realized on a chip by combining IV-based semiconductor substrates and flip-chip AlGa1-nAsSb/GaSb based photodetectors and embedded electronics for signal processing. Embodiments of the invention may be applied for real-time monitoring of critical blood analyte concentration levels such as lactates, urea, glucose, ammonia, albumin, etc.

A discrete wavelength tunable laser having an optical cavity which comprises: a reflective semiconductor optical amplifier (SOA); a demultiplexer (Demux) having a single input and a plurality of outputs, the Demux configured to receive the output of the SOA and to produce a plurality of fixed spectral passbands within the gain bandwidth of the SOA; one or more tunable distributed Bragg reflector(s) (DBR(s)) arranged to receive the outputs of the Demux, each tunable DBR configured to select a reflective spectral band within the gain bandwidth of the SOA upon application of a bias current; wherein the SOA forms the back end mirror of the optical cavity; the one or more tunable DBRs form the front end mirror of the optical cavity; and wherein the lasing channel of the discrete wavelength tunable laser is chosen by the overlap of the selected reflective spectral band of one of the one or more tunable DBRs with a fixed spectral passband of the Demux.

A gain medium is pumped by a source. An optical wave passes through a photonic integrated circuit (PIC) that comprises: a substrate comprising Silicon, a plurality of photonic structures, an input port coupling an optical wave into a waveguide formed in the PIC, and an output port coupling an optical wave out of a waveguide formed in the PIC. Propagation of an optical wave circulating around a closed path of a laser ring cavity is limited using an optical isolator such that, when the pump source exceeds a lasing threshold, the optical wave propagates in a single direction through the gain medium and the PIC. From output coupler, an output that is provided that comprises a fraction of the power of an optical wave that is incident upon the output coupler, and remaining power of the optical wave is redirected around the closed path of the laser ring cavity. The fraction can be greater than 0.5.

A technology is described for a Photonic Integrated Circuit (PIC) radio frequency (RF) oscillator. The PIC RF oscillator can comprise an optical gain media coupled to a first mirror and configured to be coupled to the PIC. The PIC can comprise a first optical cavity located within the PIC, a tunable mirror to form a first optical path between the first mirror in the gain media and the first tunable mirror, and a frequency tunable intra-cavity dual tone resonator positioned within the first optical cavity to constrain the first optical cavity having a common optical path to produce tow primary laser tones with a tunable frequency spacing. A photo detector is optically coupled to the PIC and configured to mix the two primary laser tones to form an RF output signal with a frequency selected by the tunable frequency spacing of the two primary tones.

A semiconductor optical device includes an SOI substrate having a waveguide of silicon, and at least one gain region of a group III-V compound semiconductor having an optical gain bonded to the SOI substrate. The waveguide has a bent portion and multiple linear portions extending linearly and connected to each other through the bent portion. The gain region is disposed on each of the multiple linear portions.