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Laser Diode Pulser Using Resonant Quantum Well Devices

IP.com Disclosure Number: IPCOM000036325D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 3 page(s) / 103K

Publishing Venue

IBM

Related People

Chiu, GLT: AUTHOR [+2]

Abstract

A device with negative dynamic conductance region can be used to convert voltage ramps into electrical current pulses. Fig. 1 illustrates this conversion process using an I-V curve. Tunnel diodes and resonant tunneling diodes are familiar examples that exhibit negative dynamic conductance.

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Laser Diode Pulser Using Resonant Quantum Well Devices

A device with negative dynamic conductance region can be used to convert voltage ramps into electrical current pulses. Fig. 1 illustrates this conversion process using an I-V curve. Tunnel diodes and resonant tunneling diodes are familiar examples that exhibit negative dynamic conductance.

By incorporating this circuit with a laser diode (Fig. 2), one can generate short laser pulses. Recently, it has been shown that the resonant tunneling double- barrier diode can modulate current up to several milliamperes (see, e.g., Fig. 4 of
1). This is sufficient to turn on low-threshold (N mA 2) laser diodes without the DC bias circuitry shown in Fig. 2. Both laser diodes and resonant tunneling diodes can be integrated on GaAs or InP substrates; thus a very compact laser diode pulsing circuit can be achieved with this active source modulation approach. Laser diodes and resonant tunneling diodes have been modulated up to 46 GHz 3 and 56 GHz 1, respectively. It is not expected that the high speed performance of non-integrated technology using, e.g., step recovery diodes as pulsing source for laser diodes, can match that of integrated laser diodes with resonant tunneling diodes.

It is difficult to generate voltage ramps at a multi-gigahertz frequency. Sinusoidal waveforms could be used in place of the sawtooth waveforms. In this case, only the positive portion of the sine wave generates laser light. (The negative portion r...