Fiber lasers and optoelectronic devices based on few layers of

graphene

Workshop CPqD / Bristol University Program

Lúcia A. M. SaitoMackgraphe - Centro de Pesquisas Avançadas em Grafeno,

Nanomateriais e NanotecnologiaMackenzie Presbyterian University

2014

Outline

Part I - Previous work:

• Actively mode-locking Erbium fiber lasers with meters and kilometers long

• In-field and in-laboratory 50 km ultralong Erbium-doped fiber lasers

Part II - Future Interests:

• Graphene Properties

• Graphene-based optical modulators

– Electroabsorption modulator based on monolayer graphene

– Double-Layer Graphene Optical Modulator

– MZ Graphene Optical Modulator

• Final remarks

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Previous work:Actively mode-locking Erbium fiber lasers

with meters and kilometers long

Ultralong Erbium-doped Fiber Lasers

Length of 10 cavities: 16.4 m to 100.8 km Total intracavity loss: 3.7 to 22.9 dB. Erbium-doped fiber:

• Absorption coefficient: -33.8 dB/m• Dispersion coefficient: -57.0 ps/nm.km

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Pave = 1.8 mW

Pulse Width as a function of Dispersion and Cavity Length

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Analysis of Dispersion and Nonlinearity LengthSetup Lcav LD (km) LNL (km) Lcav / LD Lcav / LNL Analysis

1 16.4 m 36.59 3.06 0.0005 0.0054 I – Neither dispersive nor

nonlinear effects2 51.6 m 12.54 2.41 0.0041 0.0214

3 218.0 m 12.74 2.61 0.0171 0.0835

4 1.4 km 11.63 2.56 0.1204 0.5469 II – Nonlinearity-dominant regime

(Lcav ~ LNL)5 3.0 km 13.49 2.73 0.2224 1.0989

6 12.6 km 14.36 2.80 0.8774 4.5000III – Dispersion

(Lcav ~ LD)and nonlinearity-dominant regime

(Lcav > LNL)

7 25.3 km 18.82 3.26 1.3443 7.7607

8 50.6 km 44.26 4.92 1.1432 10.2846

9 75.7 km 65.85 6.00 1.1496 12.6167

10 100.8 km 83.74 6.76 1.2037 14.9112

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Possibility of soliton formation in all cavity setups.

Analysis of Soliton Power and Soliton Period as a function of D and Lcav

The parameter Z / Lcav is constant (~1.35) for ultralong cavities.

Analysis of Output Spectrum

The profiles of the spectrums confirm the dynamics of pulses in ultralong cavities. 8

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In-field(Kyatera Network)

50 km Ultralong Erbium Fiber Lasers(in-lab and in-field)

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Dispersion and nonlinear effects change the pulse duration at low modulation frequency.

Pulse duration is shorter than

expected by theory

Output Pulse Width as a functionof Modulation Frequency

Future Interests:Optoelectronic devices based on

few layers of graphene

K. S. Novoselov et al., Nature Vol. 490, p.192 (2012).

Graphene-based photonics applications:Possible application timeline, enabled by continued advances in graphene technologies, based on projections of products requiring advanced materials such as graphene. The figure gives an indication of when a functional device prototype could be expected based on device roadmaps and the development schedules of industry leaders.

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Graphene Properties• High-speed operation. Graphene-based electronics may have the

potential to operate at THz, depending on the carrier density and graphene quality.

• Strong light-graphene interaction. In comparison to compound semiconductors, a monolayer of graphene possesses a much stronger interband optical transition.

• Broadband operation (300 to 2500 nm for SLG). The optical absorption of graphene is independent of wavelength.

M. Liu et al., Nature, Vol. 474, p.64 (2011).

Objective: to investigate optoelectronic properties and to develop the photonic devices based on few layers of graphene.

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• Monolayer graphene sheet • Device length: 40 μm• Broad optical bandwidth: 1350 to 1600 nm.

M. Liu, X. Zhang, paper OTu1l.7, OFC/NFOEC 2012.

Graphene-based optical modulators

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Electroabsorption modulator based on monolayer graphene

Modulation depth:0.1 dB/ μm

DC measurement of the modulator:

Electro-optics response of the device:

Frequency limit: 1.2 GHz(measured 3 dB bandwidth)

Drive voltages: 2.0 to 3.5 V

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Double-Layer Graphene Optical Modulator

M. Liu, X. Yin, X. Zhang, Nano Letters Vol. 12, p.1482-1485 (2012)

• Modulation depth: ~0.16 dB/μm• Modulator operates at 1 GHz• Device length: 40 μm• Double-layer

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Mach-Zehnder modulator

• 8 graphene layers• Theoretical• Footprint: 4 x 30 μm2

• High modulation efficiency: 20V. μm• Large extinction ratio: 35 dB• Electro-refraction effect• Variation of effective mode index

neff: 0.028• Short arm length: 27.57 μm

R. Hao et al., Applied Physics Letters Vol. 103, 061116 (2013) 19

Ultra-compact optical modulator by graphene induced electro-refraction effect

R. Hao, W. Du, H. Chen, X. Jin, L. Yang, E. Li, Applied Physics Letters Vol. 103, 061116 (2013)

• Chemical potential is fixed μc1 = 1 eV.• Large extinction ratio: 35 dB

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Final Remarks

Research Interests:• Development of optoelectronic devices such as modulators based on few

layers of graphene.• Pulses generation in Erbium fiber lasers at ultrahigh repetition rates.

Lúcia Saitolucia.saito@mackenzie.br

Mackgraphe - Centro de Pesquisas Avançadas em Grafeno, Nanomateriais e Nanotecnologia

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