Resonatorless Optical Bistability Based on Increasing Nonlinear Absorption

Hennebeger, F.; Rossmann, H.

doi:10.1002/pssb.2221210227

Cited by 75 publications

(7 citation statements)

References 12 publications

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“…(5) Theabove expressions indicate that forlow incident intensity, the exciton density in the crystaiwill be small (N=O), and the absorption coefficient will thus be a function of frequency and temperature. The crystal absorptivity will then be determined by phonon relaxation of the exciton.…”

Section: Statement Of the Problemmentioning

confidence: 99%

<title>Temperature variation of optical bistability of a semiconductor</title>

1993

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The effect of the phonon subsystem of a crystal on laser absorption is considered. The exciton-phonon interaction is shown to result in a nonlinear behavior of absorption as a function of exciton gas density. The output light intensity is calculated as a function of temperature and the temperature range in which optical bistability occurs is established. INTRODUCTIONBistability is understood as the existence of two stable states at the output of a crystal for a fixed set of input parameters, and is known to be inherent in a variety of materials and devices. The discovery of the optical bistability (OB) in the early ,2 has given rise to a new prospective line of research in the nonlinear optics of condensed media. The OB presents considerable practical interest because of its potential usefulness in creating optical transistors, switches, memories and other optoelectronic devices which are free from transit-time effects.Although a variety of techniques for producing OB have been developed, three major components are usually necessary, i.e. a light source (laser) , a nonlinear medium (usually a semiconductor) ,andan external feedback (usually provided by a Fabry-Perot laser cavity)3'4. In the above arrangement, OB is achieved at rather low light intensities. However, there are difficulties associated with cavity fabrication, strict coherence and monochromaticity requirements, and high sensitivity of the cavity to external factors such as temperature variations, etc. Thus, a wide search for OB systems using no cavities is currently in progress.First theoretical studies of cavityless OB appeared in 1984 5,6• In these, the absorption nonlinearity associated with the increase of the exciton density was first approximated, and then dynamical OB model was constructed. The nature of the above nonlinearity has been the subject of a number of studies. Schmidt et al.7 explained OB by bandgap narrowing due to exciton screening by electron-hole plasma. Lambsdorf8 developed a temperature theory of OB in which the band edge displacement takes place as a result of crystal heating by a laser beam. Chemla and Miller9 explained the increase of the absorption nonlinearity by local field effects. The present authors10 associate the absorption nonlinearity with a shift of the exciton level due to exciton-exciton interaction. The principal disadvantage of the above theories is that they all require high external radiation intensities when exciton-exciton interaction sets in or exciton break-up resulting in the formation of a high-density electron-hole plasma takes place, whereas in practice several mW laser intensity is sufficient to produce cavityless 0B11. Other theories employ mostly an empirical absorption coefficient-exciton density relationship.In the present study, the exciton-phonon interaction is considered as a possible mechanism of dynamic nonlinearity. STATEMENT OF THE PROBLEM.To establish the relationship between the output signal (IB) and the incident laser intensity (I) and input parameters of the system, we apply here th...

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Section: Statement Of the Problemmentioning

confidence: 99%

<title>Temperature variation of optical bistability of a semiconductor</title>

1993

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“…Neglecting recombination, the characteristic time which the front needs to bleach a characteristic penetration depth -given by the absorption length U , / ( r W A N A ) -is determined by z = l/(wAN,,h(+, t)) (see (21)). N,,(z,, t) represents the photon density at time t at the position zF of the front.…”

Section: Z(t)/(hwv)mentioning

confidence: 99%

“…2). To illustrate our definition of the term front, the statics of the model given by (21) to (24) is solved in the Appendix.…”

Section: Switching Frontsmentioning

confidence: 99%

Nonlinear Dynamics of Optical Switching Fronts in CdS

Schmolke

Schöll

Nägele

et al. 1995

Physica Status Solidi (b)

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A two-level model for impurity-related optical switching in lightly doped CdS crystals is developed which explains dynamical switching between a low and a high transmissivity state by a bleaching front traversing the crystal with a velocity of several lo8 cm/s and offers detailed insight into the internal nonlinear spatio-temporal dynamics of the process. The predicted front is detected experimentally by a 90" pump-and-probe configuration. The front velocity in the experiment agrees well with the theoretical prediction.

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“…Режим безрезонаторной абсорбцион-ной ОБ вблизи сильно выраженного экси-тонного резонанса (X > Х ех ), связанный с увеличивающимся при росте уровня воз-буждения нелинейным поглощением (а (п)), осуществлен в 13 > 14 . Собственная ОС возни-кала при доминировании процесса генерации частиц над рекомбинацией 15 . Немонотонный рост а с ростом концентрации частиц п может быть связан 15 с переходом Мотта, с увеличе-нием затухания в области крыла линии экси-тонного поглощения, с образованием экси-тонных молекул и с перенормировкой ши-рины запрещенной зоны 14 при двухфотонном возбуждении плазмы.…”

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Optical bistability in semiconductors

Днепровский¹

1985

Usp. Fiz. Nauk

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Resonatorless Optical Bistability Based on Increasing Nonlinear Absorption

Cited by 75 publications

References 12 publications

<title>Temperature variation of optical bistability of a semiconductor</title>

<title>Temperature variation of optical bistability of a semiconductor</title>

Nonlinear Dynamics of Optical Switching Fronts in CdS

Optical bistability in semiconductors

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