Design of Novel Unapodized and Apodized Step-Chirped Quasi-Phase Matched Gratings for Broadband Frequency Converters Based on Second-Harmonic Generation

Tehranchi, Amirhossein; Kashyap, Raman

doi:10.1109/jlt.2007.909862

Cited by 50 publications

(22 citation statements)

References 23 publications

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“…For example, an effective apodization technique has been proposed to broaden and flatten the wavelengthconversion bandwidth by engineering patterns of QPM step-chirped gratings in poled lithium niobate (LiNbO 3 ) waveguides. 9 This technique has been used to achieve bandwidths of approximately 40 nm with SHG conversion efficiencies of approximately 212 to 220 dB (6.3%-1%). In the case of another design based on engineered inverted domains in the form of step-chirped gratings in MgO-doped poled LiNbO 3 waveguides, the achieved efficiency curves have indicated a bandwidth as large as 65 nm and an SHG conversion efficiency of 222.5 dB (,0.56%).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous broadband generation of second and third harmonics from chirped nonlinear photonic crystals

et al. 2014

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Ultrabroadband laser sources are highly desirable in a wide variety of modern science disciplines ranging from physics, chemistry and materials science to information communications and processing. Here we present the design and fabrication of a chirped periodically poled lithium niobate (CPPLN) nonlinear photonic crystal that supports multiple orders of quasiphase matching with finite bandwidth and allows for the simultaneous broadband generation of second and third harmonics with high conversion efficiency. Moreover, the chirp rate has a significant influence on the conversion efficiency and bandwidth. The CPPLN scheme offers a promising approach for the construction of short-wavelength laser sources and enables the generation of the three primary colors-red, green and blue-from a single crystal, which may have potential applications in large-screen laser displays. Keywords: chirped periodically poled lithium niobate; quasiphase matching; second-harmonic generation; third-harmonic generation INTRODUCTION Ultrabroadband laser sources are highly desirable in a wide variety of modern science disciplines ranging from physics, chemistry and materials science to information communications and processing. Laser gain media that are capable of short-pulse generation are available but limited, and they cover only a small portion of the optical spectrum. Shortly after the creation of the first laser in 1960, the door to nonlinear optics was opened because of the discovery of second-harmonic generation (SHG).1 Broad-bandwidth and high-conversion-efficiency SHG, third-harmonic generation (THG), higher-order-harmonic generation and various frequency-mixing and parametric-conversion processes have all provided fascinating routes toward the considerable expansion of the spectral range of laser sources.To realize high-efficiency SHG, THG and other optical parametric processes, nonlinear optical materials are required to simultaneously satisfy the phase-matching condition and possess large nonlinear optical coefficients in the phase-matching direction. Although many natural nonlinear crystals have large nonlinear coefficients in certain directions, proper phase matching cannot always be achieved because of the dispersion of the material. Thus, the optical birefringent properties of certain birefringent nonlinear crystals are often utilized to compensate for the material dispersion and achieve phase matching. However, the stringent conditions for birefringent phase matching greatly limit the extension of the optical frequency. As an alternative approach, quasiphase matching (QPM), which was first proposed in 1962, 2 launched a new era in nonlinear optics because of several advantages it offers over conventional birefringence phase matching in the frequency-conversion process. These advantages include phase matching in materials that have high nonlinear optical coefficients but

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Section: Introductionmentioning

confidence: 99%

Simultaneous broadband generation of second and third harmonics from chirped nonlinear photonic crystals

et al. 2014

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“…For a constant length, doubling the sections, nearly doubles the bandwidth and halves the efficiency. On the other hand, for a constant length, doubling the grating period increment, roughly doubles the bandwidth and halves the efficiency [12]. Consequently, doubling the sections and halving the chirp period gives approximately the same result.…”

Section: Theory and Modelmentioning

confidence: 92%

“…It is seen that with increasing r, it is possible to obtain improved and different forms of efficiency curves with decreased bandwidths. On the other hand, for the same length, the ASCG reduces the number of sections and therefore increases the changes in the number of the poled region or the duty cycle [12,13]. Thus, increasing the change in the chirp period and the change in the duty cycle makes the fabrication of the apodized step-chirped gratings more convenient.…”

Section: Bandwidth Enhancement and Response Flatteningmentioning

confidence: 99%

High-efficiency pump-resonant quasi-phase-matched frequency doublers with flattop broadband responses

Tehranchi

Kashyap

2009

Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications III

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“…1, where the sample was divided into uniform domains, for the superlattice of ferroelectrics is essentially a digitized structure with a local nonlinear coefficient d eff (x) that is either plus or minus that of the material. Although the smaller domain width is, the better optimal AOS grating will perform, the smallness of domain width less than 3 μm will introduce poling difficulties with aforesaid engineering methods [6]- [10] and we consequently chose L 0 = 3μm as the domain width for easing fabrication, which is less than the coherence length of 9.7 μm. The optimal domain distribution was then created by the simulated annealing (SA) method [15] by selecting appropriate objective function to achieve flat efficiency response with an arbitrary degree of band broadening.…”

Section: Operation Principles and Numerical Design Of Aos Gratingsmentioning

confidence: 99%

“…Recently an efficient wideband with flat efficiency response has been numerically proposed using the step-chirped grating with fixed pumps to efficiently suppress the unwanted ripples instead of the uniform grating with detuned pumps [8]. Another technique has also proved to be useful to solve the problem by changing the duty ratio at both ends of a chirped or step-chirped grating [9], [10], or by using a deletedreversal pattern [11]. However, the smallness of the initial inverted domain width below 2 μm scale is still a challenge to avoid the efficiency fluctuation and to put into practical applications.…”

Section: Introductionmentioning

confidence: 99%

Performance Enhancement for Ultrashort-Pulse Wavelength Conversion by Using an Aperiodic Domain-Inverted Optical Superlattice

Dang

Chen

2012

IEEE Photon. Technol. Lett.

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We propose a designed aperiodic domain-inverted optical superlattice structure, where the performance of ultrashort-pulse wavelength conversion, relative-broad and flat conversion band with high conversion efficiency, has been wellbalanced and enhanced in comparison with those in periodical or linear-chirped optical superlattices. Using this structure, we present a 5.5-nm flat band with almost no pulse distortion for picosecond wavelength conversion in the C-band. Moreover, the uniformity of all inverted domains may provide more convenience for poling. The above benefits may bring promising applications in generating broadband continuous-variable entanglement source and terahertz source with equivalent generation rate.

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Design of Novel Unapodized and Apodized Step-Chirped Quasi-Phase Matched Gratings for Broadband Frequency Converters Based on Second-Harmonic Generation

Cited by 50 publications

References 23 publications

Simultaneous broadband generation of second and third harmonics from chirped nonlinear photonic crystals

Simultaneous broadband generation of second and third harmonics from chirped nonlinear photonic crystals

High-efficiency pump-resonant quasi-phase-matched frequency doublers with flattop broadband responses

Performance Enhancement for Ultrashort-Pulse Wavelength Conversion by Using an Aperiodic Domain-Inverted Optical Superlattice

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