Photoelectrochemical laser interference etching for fabrication of 235 nm diffraction gratings on
            <i>n</i>
            -InP

Backlin, L.

doi:10.1049/el:19870470

Cited by 8 publications

(3 citation statements)

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“…The first inequality (8) means that gain is small over distances of the order of a wavelength )Jn0 in optical medium, A = 2rc/w being the wavelength of light in vacuum. The second and third inequalities (8) imply that the perturbations of the refractive index and gain constant are small.…”

Section: Introductionmentioning

confidence: 99%

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New concept of single-mode resonator for distributed feedback semiconductor and fiber lasers

et al. 1995

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The new concept of single-mode resonator for single-frequency distributed feedback (DFB) lasers is presented. This concept is based on embedded nonharmonic distributed Bragg structure with sinusoidally modulated coupling coefficient, which is a combination of two superimposed sinusoidal Bragg gratings of equal heights and slightly different periods. Resonant frequencies and corresponding threshold gains of such distributed resonator are calculated theoretically by using the coupled-mode theory. The designed resonator provides stable single-frequency oscillation and has lasing characteristics (frequencies and thresholds) very similar to those of well-known distributed resonator with quarter-wavelength shift. The developed concept of resonator with sinusoidally modulated coupling coefficient can be applied both to semiconductor laser diodes with incorporated Bragg relief grating and to DFB fiber lasers with refractive index grating. The important advantage of designed new single-mode Bragg structure, as compared to quarter-wavelength-shifted structure, is that it can be fabricated very easily on semiconductor surfaces and in photosensitive fibers by direct three-beam holographic writing. . INTRODUCTIONDistributed feedback (DFB) semiconductor and fiber lasers with incorporated submicron Bragg relief or refractive index grating are widely used in optoelectronics and integrated optics as reliable sources of narrow-band coherent radiation for 1 .3 -1 . 5 um wavelength region. They possess very high degree of spectral selectivity due to very narrow frequency bandwidth of Bragg resonance. For example, DFB fiber laser with embedded sinusoidal index grating provides two-mode oscillation with resonant frequencies w1 and w1 slightly above and below the Bragg frequency WBr, the frequency interval &o = w1 -(Oi between these modes being Aw/WB. A/Ln, where i% is lasing wavelength, L is resonator length, n is effective mode index.4'6The progress of integrated optics and long-haul fiber communication networks imposes new hard requirements on lasing characteristics of DFB laser sources and among them the requirement of stable single-frequency oscillation is of great importance. It is well known2'3'5'6 that DFB lasers with incorporated harmonic Bragg grating (of sinusoidal, triangular, trapezoidal form, etc) can not provide single-frequency oscillation, since in this case two modes of different frequencies in the vicinity of WBr have equal thresholds. Various methods were developed to achieve the stable singlefrequency oscillation of DFB lasers. One of these methods, which is widely used now, is the utilization of distributed resonator with quarter-wavelength shift.2'7 Such distributed resonator consists of two sections with embedded harmonic Bragg gratings of equal periods d and depths h, having phase shift r at the centre of laser cavity, which results in stepped modulation of coupling coefficient along the resonator. In this case the mode with w = WBr has the lowest threshold. It provides the stable single-mode oscillation at Bra...

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Section: Introductionmentioning

confidence: 99%

“…The second and third inequalities (8) imply that the perturbations of the refractive index and gain constant are small. The inequalities (8) allow us to write the electric permittivity (z) (6) of optical laser medium as E(z) n + i2nm0 + 2n [n (z) + im1(z)] cos(gz + çô) .…”

Section: Introductionmentioning

confidence: 99%

New concept of single-mode resonator for distributed feedback semiconductor and fiber lasers

et al. 1995

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“…The grating can be fabricated either by using a holographic technique based on laser beam interference [2], [3] or by using electron beam lithography (EBL) [4]. EBL has many advantages compared to holographic methods.…”

Section: Introductionmentioning

confidence: 99%

The effect of stitching errors on the spectral characteristics of DFB lasers fabricated using electron beam lithography

Kjellberg

Schatz

1992

J. Lightwave Technol.

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We present the first comprehensive investigation on field stitching errors and their effect on the single-mode characteristics of DFB lasers fabricated using electron beam lithography. The stitching errors are associated with small-area, high-resolution electron beam exposure, which has the potential advantage of high-speed writing of laser gratings. Measurements show that the errors are composed of a systematic and a stochastic part. Their effect on the gain margin was simulated both for X/4 phase-shifted and optimized multiple-phase-shifted DFB lasers. Simulations show that the lasers are insensitive to the systematic part of the stitching errors if the number of errors is large enough.The stochastic part was found to give rise to a variation in gain margin of the DFB lasers. We have concluded that the field stitching accuracy in the high-resolution mode of a commercial system for electron beam lithography is sufficient to provide a high yield of single-mode lasers. However, it is essential that certain precautions are taken considering exposure conditions, and that a fault tolerant laser design is used.

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Pattern formation techniques in photochemical etching

Ashby

1992

Thin Solid Films

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Photoelectrochemical laser interference etching for fabrication of 235 nm diffraction gratings on n -InP

Cited by 8 publications

References 1 publication

New concept of single-mode resonator for distributed feedback semiconductor and fiber lasers

New concept of single-mode resonator for distributed feedback semiconductor and fiber lasers

The effect of stitching errors on the spectral characteristics of DFB lasers fabricated using electron beam lithography

Pattern formation techniques in photochemical etching

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