Northern Telecom Limited

Northern Electric Company Limited

John C Dyment

Anthony J Springthorpe

Kiu-Chi D Chik

Tibor F Kovats

Jozef Straus

Christopher M Look

Tibor F Devenyi

William J Sinclair

Kiuchi D Chik

A method for screening double heterostructure laser diodes before mounting and packaging is disclosed. At a normal laser diode operating temperature, a range of pulsed current is passed through the laser diode and the lasing threshold current and slope efficiency of the laser diode are monitored. The laser diode is then subjected to a burn-in process in which it is driven at a high junction temperature for an extended time period. Subsequently the lasing threshold current and slope efficiency are again monitored by applying the same range of pulsed current at the normal operating temperature. If either the threshold current or the slope efficiency have changed by more than a predetermined amount, the laser diode is rejected. Otherwise, the laser diode is gauged as likely to have a lifetime greater than a predetermined value at normal operating conditions so warranting further testing prior to installation into a laser package.

Method for screening laser diodes

Semiconductor lasers exhibit transient relaxation oscillation on start-up and specific lasers often exhibit sustained spontaneous pulsations caused probably by crystalline defects. These fluctuations are suppressed in a laser having an integrally formed light emitting diode (LED) which generates spontaneous light which is coupled into the laser by virtue of the close proximity of the laser and the light emitting diode.

Semiconductor lasers with integrally formed light emitting diodes

Semiconductor lasers exhibit transient relaxation oscillations on start-up and specific lasers often exhibit sustained spontaneous pulsations caused probably by crystalline defects. These fluctuations are suppressed by coupling laser emission into a 0.3 to 2 cm. length of waveguide and coupling light reflected from the end of the waveguide back into the laser. Embodiments disclosed include one utilizing a length of optical fibre, while others are integrated optical structures.

Methods for simultaneous suppression of laser pulsations and continuous

An electro-optic device for stabilizing the output level of a Burrus-type light emitting diode (LED) utilizes a photodiode to monitor side emission from an active region of the LED. Side emission closely tracks top emission, which is launched into an output fiber. An electrical analog is derived from the monitored side emission and is applied in a feedback loop to control modulation level or bias current to the LED. In this way, peak optical output (for digital systems) or r.m.s. output and linearity (for analog systems) is stabilized. The monitoring photodiode and the LED may be spatially separate or may form a unitary structure.

Electro-optic devices

A double heterostructure laser has a first confining layer on the substrate, an active layer on the first confining layer and a second confining layer on the active layer. A groove is etched through the second confining layer and active layer to form a reflecting surface at approximately 45.degree. to the plane of the active layer. The resonant cavity is formed between a cleaned end surface and a surface at the substrate. A hole through the substrate to the first confining layer is aligned with the reflecting surface for emission therethrough.

Double heterostructure laser for direct coupling to an optical fiber

In an optoelectronic device, light is restrained from propagating in one or both confining layers on either side of an active layer by forming one or more photon absorbing barriers in one, or both, confining layers. A photon absorbing barrier can be formed by proton bombardment of a confining layer, by producing a protrusion from the substrate into the adjacent confining layer, or by producing a protrusion from a capping layer into the other confining layer, or by combinations of these. Spaced apart barriers can define a device, or sections of a multisectioned device, for example a monolithic light emitting diode and modulator.

Method of producing optoelectronic devices with control of light

In an optoelectronic device, light is restrained from propagating in one or both confining layers on either side of an active layer by forming one or more photonabsorbing barriers in one, or both, confining layers. A photon absorbing barrier can be formed by proton bombardment of a confining layer, by producing a protrusion from the substrate into the adjacent confining layer, or by producing a protrusion from a capping layer into the other confining layer, or by combinations of these. Spaced apart barriers can define a device, or sections of a multi-sectioned device, for example a monolithic light emitting diode and modulator.

In an optoelectronic device, light is restrained from propagating in one or both confining layers on either side of an active layer by forming one or more photon absorbing barriers in one, or both, confining layers. A photon absorbing barrier can be formed by proton bombardment of a confining layer, by producing a protrusion from the substrate into the adjacent confining layer, or by producing a protrusion from a capping layer into the other confining layer, or by combinations of these. Spaced apart barriers can define a device, or sections of a multi-sectioned device, for example a monolithic light emitting diode and modulator.

Optoelectronic devices with control of light propagation

A photodiode detector comprises a substrate on which a plurality of detector sections are formed, in series. Reverse bias is applied to the separate sections, the bias more negative for each section from the input end. The absorption bandwidth for each section can vary and the bandwidth of a section can be variable.

Growing community of inventors

Kanata, Canada

John C Dyment