Erbium-implanted high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Q</mml:mi></mml:math>silica toroidal microcavity laser on a silicon chip

Min, Bumki; Kippenberg, Tobias J.; Yang, Lan; Vahala, Kerry J.; Kalkman, Jeroen; Polman, A.

doi:10.1103/physreva.70.033803

Cited by 97 publications

(83 citation statements)

References 33 publications

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“…For further details on this theoretical optimum threshold, we refer the reader to Ref. 11. We found that for a toroid with a principal diameter of 60 m and intrinsic quality factor ͑pump mode͒ between 5 ϫ 10 6 and 1 ϫ 10 7 , thresholds in the range of 400-600 nW can be achieved with an Er 3+ concentration of 2 ϫ 10 19 cm −3 .…”

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confidence: 95%

“…11 This optimal erbium ion concentration depends, in turn, on the intrinsic quality factor of the pump mode. 11 In the low concentration limit, the threshold power increases sharply because Er 3+ ions are not able to give sufficient gain required for loss compensation; while in high concentration limit, the threshold again increases due to increases of concentrationdependent loss mechanism, such as upconversion and ionpair induced quenching. For further details on this theoretical optimum threshold, we refer the reader to Ref.…”

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confidence: 99%

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Erbium-doped and Raman microlasers on a silicon chip fabricated by the sol–gel process

Yang¹,

Carmon²,

Min³

et al. 2005

Applied Physics Letters

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148

117

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We report high-Q sol-gel microresonators on silicon chips, fabricated directly from a sol-gel layer deposited onto a silicon substrate. Quality factors as high as 2.5ϫ 10 7 at 1561 nm were obtained in toroidal microcavities formed of silica sol-gel, which allowed Raman lasing at absorbed pump powers below 1 mW. Additionally, Er 3+ -doped microlasers were fabricated from Er 3+ -doped sol-gel layers with control of the laser dynamics possible by varying the erbium concentration of the starting sol-gel material. Continuous lasing with a threshold of 660 nW for erbium-doped microlaser was also obtained. Recently, a chip-based silica resonator structure in the form of a microtoroid has demonstrated ultrahigh-Q-factors in the range of 100 million. 1 By coating these high-Q microcavities with erbium-doped sol-gel films 2 or by beginning with erbium implanted silica layers, 3 low threshold rareearth-doped microlasers on-a-chip have been demonstrated. In another study, the realization of integrated Raman microlasers beginning with a layer of thermally-grown silica has been achieved. 4 Microlasers on silicon chips are especially interesting because they are integrable with other optical or electric components. In this work, we demonstrate the possibility of making microlasers directly from the sol-gel layers on the silicon wafer. The sol-gel method for preparing silica and silicate from a metal alkoxide precursor provides a versatile and cost-effective way to fabricate various components on silicon chips. It combines control of composition and microstructure at the molecular level with the ability to shape materials in bulk, fiber, powder, and thin film forms. 5 This technique allows a wide variety of thin films to be deposited on various substrates. In addition, optical devices, including buried-channel erbium-doped waveguide amplifiers, microlenses, one-dimensional photonic crystal devices and external-cavity distributed Bragg reflector ͑DBR͒ laser have been achieved using the sol-gel method. 6-9 Here we report a new method to fabricate both erbium-doped microlasers and Raman microlasers on a silicon chip using sol-gel films as the base material for microtoroid formation. In one series of experiments, erbium-doped sol-gel films are used to create low threshold microlasers. In a second set of experiments, pure silica sol-gel layers are processed into ultrahigh-Q Raman microlasers. Both of these cases demonstrate the ability to use spin coating of sol-gel films as a processing alternative to deposition or oxidation methods for silica layer formation.The sol-gel solution was prepared by hydrolyzing tetraethoxysilane ͑TEOS͒ using water with the molar ratio of water to TEOS around 1-2. Hydrochloric acid was added to make the solution in acid condition. Er 3+ ions were introduced by adding Er͑NO͒ 3 to achieve the desired Er 3+ concentration. After reaction at 70°C for 3 h, a viscous solution was formed. The silica sol-gel film was then deposited on a silicon substrate by the spin-coating method. Different thicknesses of the s...

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confidence: 95%

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confidence: 99%

Erbium-doped and Raman microlasers on a silicon chip fabricated by the sol–gel process

Yang¹,

Carmon²,

Min³

et al. 2005

Applied Physics Letters

Self Cite

148

117

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“…This rule of thumb is well-known and can be rigorously derived for a Fabry-Perot cavity [15][16][17]. Similar out coupling criteria in the absence of self-saturation have also been used for fiber-coupled microcavity lasers [18][19][20].…”

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confidence: 99%

Enhancement of laser power-efficiency by control of spatial hole burning interactions

Malik

Türeci

2014

Nature Photon

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The laser is an out-of-equilibrium nonlinear wave system where the interplay of the cavity geometry and nonlinear wave interactions, mediated by the gain medium, determines the self-organized oscillation frequencies and the associated spatial field patterns. In the steady state, a constant energy flux flows through the laser from the pump to the far field, with the ratio of the total output power to the input power determining the power-efficiency. While nonlinear wave interactions have been modelled and well understood since the early days of laser theory, their impact on the power-efficiency of a laser system is poorly understood. Here, we show that spatial hole burning interactions generally decrease the power efficiency. We then demonstrate how spatial hole burning interactions can be controlled by a spatially tailored pump profile, thereby boosting the power-efficiency, in some cases by orders of magnitude.Power-efficiency of lasers is a key property to be maximized to reduce energy requirements for on-chip applications, facilitate thermal management and pack lasers into smaller volumes. Earlier work on solid-state lasers addressed the quantum design of the gain medium and the optimization of carrier transport, demonstrating strong improvements in power-efficiency [1,2]. Far less systematic work has addressed the fundamental factors limiting the power efficiency of lasers and effective methods to overcome these, taking into account specific resonator properties. In particular, the impact of spatial hole burning interactions is poorly understood [3]. A case in point are the findings of Ref. [4], where the output power of microcavity quantum cascade lasers was found to increase exponentially with boundary deformation, resulting in a power enhancement over two orders of magnitude with respect to identical lasers of circular cross-section. After more than a decade of theoretical development, the fundamental factors behind this dramatic increase in power efficiency remain unknown. The goal of this paper is to provide a theoretical analysis of the mechanisms at work that enable such dramatic improvements in laser power efficiency.Typically, the pump power in a microlaser is deposited uniformly across the entire cavity area [ Fig. 1(a)] and lasing naturally occurs in cavity modes with the longest cavity lifetimes. Here we show the existence of a maximally power-efficient "optimally out-coupled mode" that may never turn on in a uniformly pumped cavity due to spatial-hole burning interactions. We further show that a non-uniform pump distribution designed to selectively pump the optimally out-coupled mode can lead to strong power enhancements.Spatially non-uniform pump distributions can be realized by fabricating patterned contacts [5], by spatially non-uniform doping in the case of current injection lasers [6,7], or by using spatial light modulators or special lenses for optically pumped lasers [8,9] (see Fig. 1(b)). We discuss the optimal spatial profile of the pump for a given resonator to maximize the power effic...

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“…Although we did not www.intechopen.com attempt it for GaAs, a CALTECH group devised a laser baking process for achieving ultrahigh Q values of multi-millions involving a SiO2 microcavity. It is interesting to be a toroidal microcavity whose 3D WCM properties is unknown yet (Armani et al, 2003;Min et al, 2004). Fig.…”

Section: Basic Properties Of Pqr Lasersmentioning

confidence: 99%