Metrophotonics Inc.

National Research Council of Canada

Other

Jian-Jun He

Emil S Koteles

Michael Davies

Orazio Berolo

Bryant P Hichwa

Andre Delage

Andr&eacute; Delage

John Wade

Lynden Erickson

Boris Lamontagne

Michael Davis

Orazlo Berolo

Andr&eacute; Del&acirc;ge

A Delage

B Lamontagne

L Erickson

Lynden E Erickson

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.

Q-modulated semiconductor laser

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. The second cavity is tuned by varying the effective refractive index of a portion of the waveguide through an electrical means, resulting in wavelength switching among the set of discrete operating wavelengths as determined by the first cavity.

V-coupled-cavity semiconductor laser

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.

Optical dynamic gain amplifier

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.

Bidirectional multiplexer and demultiplexer based on a single echelle waveguide grating

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. Also, an angular dispersive element is present for receiving light from any one of the waveguides and for dispersing the light toward a plurality of output waveguides in dependence upon the input waveguide position and a wavelength of the light such that light directed from the first of the plurality of input waveguides toward the plurality of output waveguides has a first centre wavelength within each of the output waveguides and light directed from the second of the plurality of input waveguides toward the plurality of output waveguides has a second different centre wavelength within each of the output waveguides, the second different center wavelength different form any first center wavelength.

Resolution enhanced optical spectrometer having a fixed number of photodetector elements

A grating based optical de-interleaver useful over a wide wavelength range is presented. An echelle grating is used as dispersive element. The spectral response of the device is cyclic. The free spectral range of the grating is designed to separate wavelength channels to be de-interleaved. This device, being bi-directional will also operate as an interleaver.

Integrated optical interleaver/de-interleaver

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. Also, an angular dispersive element is present for receiving light from any one of the waveguides and for dispersing the light toward a plurality of output waveguides in dependence upon the input waveguide position and a wavelength of the light such that light directed from the first of the plurality of input waveguides toward the plurality of output waveguides has a first centre wavelength within each of the output waveguides and light directed from the second of the plurality of input waveguides toward the plurality of output waveguides has a second different centre wavelength within each of the output waveguides, the second different centre wavelength different form any first centre wavelength.

In a digital optical switch, an input waveguide and two output waveguides form a Y-shaped splitter or switch. Electrodes are positioned on each output waveguide at the junction with the input waveguide. The electrodes extend as narrow strips across the waveguides. The inner edges of the electrodes are curved to form a smooth continuation profile to the signal paths to reduce losses.

Digital optical switch

A homogeneous semiconductor waveguide structure having an undoped core layer and doped cladding layers on both sides of the core layer is proposed wherein the waveguide core is substantially thick providing polarization independence. Because of the cladding layers having low refractive index contrast with respect to the core and being on opposing sides resulting in a substantially symmetrical structure, the waveguide, can be made single-mode with low polarization sensitivity, thus improving characteristics for conducting light therein. Furthermore, the enlarged mode size increases coupling efficiency. Also, since the waveguide is grown from a single semiconductor composition lattice matched to the substrate, wafer uniformity and reproducibility are enhanced. The three layer structure reduces birefringence sufficiently that a yield enhancing etch stop layer can be added to the structure without substantially adverse effects.

Polarization independent waveguide structure

A grating based optical wavelength demultiplexer that can be used for multiple wavelength bands over a wide wavelength range is presented. The spectral response of the device is cyclic. The free spectral range of the grating is designed to be large enough to contain all the wavelength channels to be demultiplexed within a band but small compared to the overall wavelength window of the network application so that a multiplexed signal within any one of the wavelength bands within the application window can be demultiplexed by the same device. This device, being bidirectional will also operate as a multiplexer. By using such a cyclic design, an organization will not need to stock different parts for each band and thus significantly reduce the inventory cost.

Multiple band optical multiplexer and demultiplexer

A planar waveguide optical device whose wavelengths are stabilized by temperature, has an input channel, a series of output data channels, and a dispersive element, such as a diffraction grating or phase array, for directing component wavelengths of incoming light into the respective output data channels. A pair of monitor channels have a separation less than, and a width greater than, the data channels. A differential feedback arrangement controls the temperature of the demultiplexer according a differential signal received from the pair of monitor channels.

Wavelength stabilized planar waveguide optical devices incorporating a dispersive element

A passband flattened waveguide grating device and a method of designing the same are disclosed wherein the resulting spectral response has a wide flat passband and steep transitions. The method involves adjusting the phases of grating elements forming the grating to achieve the desired spectral response. The phase variation between adjacent grating elements comprises of, in addition to a multiple of 2&pgr;, a slow-varying central phase variation and an oscillatory phase variation. The resulting spectral response of the waveguide device accounts for the effect of convolution of the field distribution profiles of the input port and of the output ports of the device.

Planar waveguide grating device and method having a passband with a flat-top and sharp-transitions

A device for compensating the temperature sensitivity normally associated with an integrated optical waveguide grating device has a temperature compensating slab waveguide region. This compensating region is provided within the slab waveguide region normally present in the grating device by modifying a sub-region of a predetermined shape and dimension to change its temperature coefficient of refractive index. This method and device can be applied to reflective and transmissive diffraction gratings and to phased array waveguide gratings.

Athermal waveguide grating based device having a temperature compensator in the slab waveguide region

A device for compensating the birefringence normally associated with an integrated optical waveguide grating device has a polarization compensating slab waveguide region. This compensating region can be provided within the slab waveguide region normally present in the grating device by etching, doping, ion implanting a sub-region of a predetermined shape and dimension to change its birefringence. Alternatively, or in combination with changing the birefringence in this sub-region, electrodes can be provided for electro-optically changing the birefringence dynamically as required. This device can be applied to reflective and transmissive diffraction gratings and to phased array waveguide gratings.

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Ottawa, Canada

Jian-Jun He