Northern Telecom Limited

Tibor F Devenyi

Tibor F Kovats

Christopher M Look

John C Dyment

John C Goodwin

Kiu-Chi D Chik

Iwona Turlik

To position a light output device such as a laser diode relative to a light device such as a waveguide so as to obtain maximum coupling of light, the waveguide end facing the laser is vibrated by mechanical means to modulate the coupled light. Light is detected from a remote end of the fiber and a corresponding electrical signal is generated. Positional information contained in the oscillatory component of the signal is decoded and applied to a positioning device which then reduces misalignment between the waveguide and laser. The positioning device continuously seeks the maximum coupling position. The technique finds particular application in positioning a waveguide in a laser package prior to and during anchoring.

Laser-fiber positioner

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

During production of laser diodes, crystals on which the laser diodes are formed are subjected to two high temperature processes: diffusion and alloying. These steps are performed in a quartz process tube in an oxygen free atmosphere. At some stage in the process the crystal must be moved from a cool zone to a hot zone within the tube and this is done by means of a push rod which extends through an aperture in the diffusion tube. The conventional arrangement for sealing around the push rod acts to clamp the push rod in position. Thus, temporarily, while the push rod is being moved the seal must be partly released and its sealing action is inferior. To maintain the process atomsphere free of reactive gas there is proposed by the invention a mechanism for flooding the sealing area between the push rod and the process tube with an inert gas while the sealing means is temporarily released.

Gas seal for semiconductor processing equipment

A known electro-optic has a semiconductor laser, a temperature sensor for controlling an electrically operated cooler, and an optical fiber end portion anchored close to the laser to receive light from it. Usually the fiber is anchored by a mass of cured epoxy. This invention proposes anchoring the fiber in a mass of fusible alloy which is melted and solidified using a Peltier effect device which is driven with one polarity current to function as a heater and with a reverse polarity current to function as a cooler. Once the package is complete and the laser is operating, the temperature sensor together with the Peltier effect device functioning as a cooler are used to cool the laser.

Light emitting device package having combined heater/cooler

In a method and apparatus for bonding a semiconductor laser chip to a heatsink and testing the bond obtained, temperature in the bonding operation is regulated by passing a small fixed current through the forward biased laser and monitoring corresponding change in voltage caused by alteration of the laser pn junction temperature. Current is passed to the laser through a floating contact consisting of a conducting vacuum pick-up pressed against the laser top surface. Bond integrity is subsequently tested at low temperature by passing a dc current greater than a threshold current through the laser and measuring the resulting light output and then passing a pulsed current with identical peak current level and again measuring light output. The difference in light output is a function of the bond thermal resistance.

Growing community of inventors

Nepean, Canada

Tibor F Devenyi