Abstract: A multi-wavelength multi-port laser and router. By arranging a reflective facet at one end of the port-selection semiconductor optical amplifier and a partial reflector at one end of the wavelength-selection semiconductor optical amplifier, and cooperating with the intra-cavity wavelength router to form N×N optical resonant cavities, so that each optical resonant cavity can only emit the wavelength corresponding to the lowest round-trip loss between input and output ports. The extra-cavity wavelength router is mirrored with respect to the intra-cavity wavelength router, so that one or more wavelengths of light excited by any port-selection semiconductor optical amplifier can be transmitted from the corresponding output port of the extra-cavity wavelength router.

Abstract: An optical sensor based on a broadband light source and cascaded waveguide filters comprises a broadband light source, an input waveguide, a reference ring resonator coupled with the input waveguide, a common bus waveguide coupled with the reference ring resonator, a sensing ring resonator coupled with the common bus waveguide, an output waveguide coupled with the sensing ring resonator, and two optical power detectors. At least a portion of the sensing ring resonator is influenced by the physical parameter to be measured or in contact with an analyte. The variation of the physical parameter to be measured or the variation of the analyte induces a shift of the transmission spectrum of the sensing ring resonator. By using the cascaded filtering effect of the double resonators, the wavelength shift can be translated into a variation of the total output power. Consequently the physical parameter to be measured can be easily deduced.

Abstract: An optical sensor based on a broadband light source and cascaded waveguide filters comprises a broadband light source, an input waveguide, a reference ring resonator coupled with the input waveguide, a common bus waveguide coupled with the reference ring resonator, a sensing ring resonator coupled with the common bus waveguide, an output waveguide coupled with the sensing ring resonator, and two optical power detectors. At least a portion of the sensing ring resonator is influenced by the physical parameter to be measured or in contact with an analyte. The variation of the physical parameter to be measured or the variation of the analyte induces a shift of the transmission spectrum of the sensing ring resonator. By using the cascaded filtering effect of the double resonators, the wavelength shift can be translated into a variation of the total output power. Consequently the physical parameter to be measured can be easily deduced.

Abstract: A semiconductor laser based intra-cavity optical micro-fluidic biosensor comprises a coupled-cavity semiconductor laser, a 2×2 coupler and a phase adjustment section on one input port of the coupler. The dominant mode of the coupled-cavity laser appears in one output port of the coupler, while the adjacent mode comes out from the other output port of the coupler. The resonant frequency interval of the sensing cavity is slightly larger or smaller than one half of that of the reference cavity. Part of the sensing cavity is the sensing section which is covered by an analyte. The refractive index change of the analyte will cause the lasing mode of the coupled cavity to switch to an adjacent mode, resulting in a ?-phase change in the phase difference between the two output ports of the two resonance cavities. By applying the Vernier effect, the power ratio of the two output ports of the coupler will change and the refractive index change of the analyte can be derived.

Abstract: An integrated single-fiber multi-directional transceiver such as a diplexer or triplexer for FTTH applications comprises at least a laser for transmitting a first signal at a first wavelength, a photodetector for receiving a second signal at a second wavelength, and a 2×2 optical coupler. The 2×2 optical coupler has four ports, of which port 1 connects to a fiber through an input/output waveguide, port 2 leads to the photodetector through another waveguide, port 3 and port 4 are connected with the gain waveguide and are placed inside the laser cavity. Light emitted by the gain waveguide inside the laser cavity at port 3 of the coupler is partially coupled to port 4 as a feedback for the laser and partially coupled to port 1 which couples to the optical fiber to transmit the first signal. On the other hand, the second signal at the second wavelength that is launched into the coupler from the input/output waveguide at port 1 is entirely coupled to port 2 that leads to the photodetector.

Abstract: A semiconductor laser comprises two optical ring resonators, each comprising an optical waveguide electrically pumped to provide optical gain. The two ring resonators have different round-trip optical path lengths, and are coupled to each other through a half-wave optical coupler. The half-wave optical coupler has a predetermined cross-coupling coefficient and a 180-degree cross-coupling phase. The cross-coupling coefficient is substantially less than the self-coupling coefficients in order to achieve an optimal single-mode selectivity of the laser. The first ring resonator has an optical path length such that its resonant wavelengths correspond to a set of discrete operating channels. The second ring resonator has a slightly different length so that only one resonant wavelength coincides with one of the resonant wavelengths of the first ring resonator over the operating spectral window. The lasing action occurs at the common resonant wavelength.

Abstract: An integrated single-fiber multi-directional transceiver such as a diplexer or triplexer for FTTH applications comprises at least a laser for transmitting a first signal at a first wavelength, a photodetector for receiving a second signal at a second wavelength, and a 2×2 optical coupler. The 2×2 optical coupler has four ports, of which port 1 connects to a fiber through an input/output waveguide, port 2 leads to the photodetector through another waveguide, port 3 and port 4 are connected with the gain waveguide and are placed inside the laser cavity. Light emitted by the gain waveguide inside the laser cavity at port 3 of the coupler is partially coupled to port 4 as a feedback for the laser and partially coupled to port 1 which couples to the optical fiber to transmit the first signal. On the other hand, the second signal at the second wavelength that is launched into the coupler from the input/output waveguide at port 1 is entirely coupled to port 2 that leads to the photodetector.

Abstract: A Q-modulated semiconductor laser comprises an optical gain section and an electro-absorptive modulator section, separated by a vertically etched air gap acting as a partially reflecting mirror. The modulator section is placed inside an anti-resonant Fabry-Perot cavity and acts as the rear reflector of the laser. The change of the absorption coefficient in the modulator section results in a change in the Q-factor of the laser, and consequently the lasing threshold and output power. Different embodiments are disclosed, which involve a distributed feedback (DFB) laser, a Fabry-Perot laser, a distributed Bragg reflector (DBR) laser, or a wavelength switchable multi-cavity laser. The integrated Q-modulated laser has advantages of high speed, high extinction ratio, low wavelength chirp and low cost.

Abstract: A semiconductor laser comprises two optical cavities, each comprising an optical waveguide bounded by two partially reflecting elements. The two optical waveguides are disposed on a substrate to form a substantially V-shaped geometry with substantially no cross-coupling at the open end and a predetermined cross-coupling at the closed end for achieving an optimal single-mode selectivity of the laser. The first cavity has a length such that its resonant wavelengths correspond to a set of discrete operating channels. The second cavity has a slightly different length so that only one resonant wavelength coincides with one of the resonant wavelengths of the first cavity over the operating spectral window. The lasing action occurs at the common resonant wavelength. In operation, at least a portion of the optical waveguide in each of the first and the second cavities are forward biased to provide substantially equal round-trip optical gains.

Abstract: A semiconductor laser comprises two optical ring resonators, each comprising an optical waveguide electrically pumped to provide optical gain. The two ring resonators have different round-trip optical path lengths, and are coupled to each other through a half-wave optical coupler. The half-wave optical coupler has a predetermined cross-coupling coefficient and a 180-degree cross-coupling phase. The cross-coupling coefficient is substantially less than the self-coupling coefficients in order to achieve an optimal single-mode selectivity of the laser. The first ring resonator has an optical path length such that its resonant wavelengths correspond to a set of discrete operating channels. The second ring resonator has a slightly different length so that only one resonant wavelength coincides with one of the resonant wavelengths of the first ring resonator over the operating spectral window. The lasing action occurs at the common resonant wavelength.

Abstract: A semiconductor laser comprises two optical cavities, each comprising an optical waveguide bounded by two partially reflecting elements. The two optical waveguides are disposed on a substrate to form a substantially V-shaped geometry with substantially no cross-coupling at the open end and a predetermined cross-coupling at the closed end for achieving an optimal single-mode selectivity of the laser. The first cavity has a length such that its resonant wavelengths correspond to a set of discrete operating channels. The second cavity has a slightly different length so that only one resonant wavelength coincides with one of the resonant wavelengths of the first cavity over the operating spectral window. The lasing action occurs at the common resonant wavelength. In operation, at least a portion of the optical waveguide in each of the first and the second cavities are forward biased to provide substantially equal round-trip optical gains.

Abstract: A Q-modulated semiconductor laser comprises a ?/4-phase-shifted distributed-feedback grating. Two isolated electrodes are deposited on top of the grating, and one electrode is deposited on the back side of the laser substrate as a common ground. The first top-side electrode covers a portion of the grating including the phase-shift region, and provides an optical gain for the laser when a constant current is injected. The second top-side electrode covers the remaining portion of the grating away from the phase-shift region, which acts as a Q-modulator of the laser. An electrical signal is applied on the second electrode to change the absorption coefficient of the waveguide in the modulator section, resulting in a change in the Q-factor of the laser, and consequently the lasing threshold and output power. The integrated Q-modulated laser has advantages of high speed, high extinction ratio, low wavelength chirp and low cost.

Abstract: A Q-modulated semiconductor laser comprises an optical gain section and an electro-absorptive modulator section, separated by a vertically etched air gap acting as a partially reflecting mirror. The modulator section is placed inside an anti-resonant Fabry-Perot cavity and acts as the rear reflector of the laser. The change of the absorption coefficient in the modulator section results in a change in the Q-factor of the laser, and consequently the lasing threshold and output power. Different embodiments are disclosed, which involve a distributed feedback (DFB) laser, a Fabry-Perot laser, a distributed Bragg reflector (DBR) laser, or a wavelength switchable multi-cavity laser. The integrated Q-modulated laser has advantages of high speed, high extinction ratio, low wavelength chirp and low cost.

Abstract: A dynamic gain equalizer using amplification instead of attenuation is disclosed. The device relies on integrated semiconductor optical amplifiers in line with a demultiplexer on a single integrated substrate for performing equalization of signals within each of a plurality of channels.

Abstract: A monolithically integrated wavelength switchable laser comprises three coupled Fabry-Perot cavities. The length and consequently the free spectral range of the first cavity are designed such that the resonant peaks correspond substantially to a set of discrete operating wavelengths separated by a constant channel spacing. The second cavity has a slightly different length so that only one resonant peak coincides with one of the resonant peaks of the first cavity over the spectral window of the material gain. The lasing action occurs at the common resonant wavelength. The two cavities are coupled through a third short cavity that produces a certain coupling loss and phase relationship between the first and the second cavities in order to achieve an optimal mode selectivity of the combined cavity laser. In operation, both the first and the second cavities are forward biased to provide optical gains for the laser action.

Abstract: A monolithically integrated dual-wavelength laser comprises at least three coupled Fabry-Perot cavities in tandem, each separated by a vertically etched air gap of a size that is substantially equal to an odd-integer multiple of quarter-wavelength. The first two cavities are of substantially comparable lengths and are actively pumped to provide gains to the combined cavity laser, and to produce a series of double-peaked lasing modes. The other cavity has a substantially smaller length and acts as an optical filter to select one of the doublets of the combined cavity as the lasing modes. The beating between the two modes of the dual-wavelength laser at a photodetector produces a microwave carrier signal whose frequency can be tuned by adjusting the balance of the injected currents between the two active cavities.

Abstract: A bidirectional multiplexer and demultiplexer based on a single waveguide grating is presented. In one embodiment of the invention, the device contains a multi/demultiplexer having an echelle grating disposed between a plurality of input channels and a plurality of output channel arrays. The input and output channels are assigned in a particular order, such that the multiplex and demultiplex functions have the same wavelength channels and such that the blaze angle of the grating facets are optimized simultaneously for both the multiplex and demultiplex function. Because the optical signals are multiplexed and demultiplexed by the same dispersive element, problems of mismatching performance introduced by using different optical components are obviated. The input/output waveguides of the dual-function device can be coupled to a single fiber array, thus reducing the packaging cost.

Abstract: A monolithic single-mode semiconductor laser comprises three coupled Fabry-Perot cavities in tandem, each separated by a vertically etched air gap of a size that is substantially equal to an odd-integer multiple of quarter-wavelength. The middle cavity is actively pumped to provide gains to the combined cavity laser. The other cavities are substantially transparent and act as an optical filter to select one of the longitudinal modes of the middle cavity as the lasing mode. The lengths of the two passive cavities are substantially different so that a narrow filtering function with a large free spectral range is obtained for optimal mode selectivity.

Abstract: A waveguide optical monitor is disclosed. The device has an optical input port coupled through a switch to a plurality of input waveguides. A dispersive element disperses light within the input optical waveguides toward a plurality of output waveguides. There are a plurality of photodetectors each optically coupled to an output waveguide. The photodectors are for sensing an intensity of light within the waveguide with which it is optically coupled. An optical switch in optical communication with the optical input port and for switching light received at the optical input port to one of the plurality of input waveguides.

Abstract: A waveguide optical monitor is disclosed. The device has an optical input port coupled through a switch to a plurality of input waveguides. A dispersive element disperses light within the input optical waveguides toward a plurality of output waveguides. There are a plurality of photodetectors each optically coupled to an output waveguide. The photodectors are for sensing an intensity of light within the waveguide with which it is optically coupled. An optical switch in optical communication with the optical input port and for switching light received at the optical input port to one of the plurality of input waveguides.