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Method of Modulating the Width of the Light Output Pulse of an Injection Laser

IP.com Disclosure Number: IPCOM000095882D
Original Publication Date: 1964-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Lanza, C: AUTHOR

Abstract

A narrow pulse of light can be generated by utilizing the inherent starting delay of a pulsed laser. The delay is caused by the necessity of building up an inverted population of carriers in the diode. This requires that a critical charge be injected into the diode. Since for a higher current the charge can be achieved faster, the delay is a function of input current.

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Method of Modulating the Width of the Light Output Pulse of an Injection Laser

A narrow pulse of light can be generated by utilizing the inherent starting delay of a pulsed laser. The delay is caused by the necessity of building up an inverted population of carriers in the diode. This requires that a critical charge be injected into the diode. Since for a higher current the charge can be achieved faster, the delay is a function of input current.

By modulating the amplitude of the driving current of fixed pulse width, a modulation of the light pulse width can be achieved. This has advantages over the method of varying the current pulse width since the method is faster and more convenient.

A pulse-width-modulated communication system has the following two advantages over a CW system: 1) much higher peak light power range can be obtained using pulses; and 2) it is noticed that the amplitude of laser light is very noisy. This pulse-width-modulation system eliminates the noisiness which would be retained with straight amplitude modulation of the laser light.

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