Enhancement of modulation bandwidth of laser diodes by injection locking

Wang, J.; Haldar, Manas K.; Li, Linhu; Mendis, F.V.C.

doi:10.1109/68.475769

Cited by 113 publications

(42 citation statements)

References 7 publications

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“…Several studies have predicted that the modulation bandwidth of strongly injection-locked semiconductor lasers can be significantly improved compared to the free-running case. 1,2 This is very attractive since it may allow one to achieve large modulation bandwidths with conventional semiconductor lasers at room temperature, avoiding the use of advanced devices and the need for complicated fabrication techniques. Injection lock ing influencing the modulation bandwidth of semiconductor lasers was shown experimentally and theoretically.…”

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confidence: 99%

Relative intensity noise characteristics of injection-locked semiconductor lasers

Jin

Chuang

2000

Applied Physics Letters

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An experimental and theoretical study of relative intensity noise �RIN� spectra of side-mode injection-locked Fabry-Pérot semiconductor lasers is reported. It is shown that the injection-locking technique effectively increases the relaxation oscillation frequency from 4.5 GHz �free-running mode� to 12 GHz �injection-locked mode� and enhances relaxation peaks of the slave laser RIN spectra. Results from our theoretical model, which include the key parameters for semiconductor quantum-well lasers, such as the linewidth enhancement factor, the nonlinear gain saturation coefficients, and optical confinement factor, show good agreement with our experimental results. © 2000 American Institute of Physics. �S0003-6951�00�03435-5� Considerable attention has recently been paid to injec tion locking in semiconductor lasers due to the desire to develop broader-bandwidth laser systems. Several studies have predicted that the modulation bandwidth of strongly injection-locked semiconductor lasers can be significantly improved compared to the free-running case. 1,2 This is very attractive since it may allow one to achieve large modulation bandwidths with conventional semiconductor lasers at room temperature, avoiding the use of advanced devices and the need for complicated fabrication techniques. Injection lock ing influencing the modulation bandwidth of semiconductor lasers was shown experimentally and theoretically. 3 Simpson and Liu indirectly observed the increase of the relaxation frequency 1 and presented the noise reduction for an injection-locked laser. 4 Meng, Chau, and Wu 5 reported ex perimental data directly demonstrating the improvement of modulation responses. Measurements of the eye diagrams of injection-locked lasers also confirm the bandwidth improvement. 6 However, little experimental work on the relative inten sity noise �RIN� and the variation of the relaxation oscilla tion frequency for injection-locked semiconductor lasers are available in the literature. 4,7 Several theoretical simulations of noise characteristics have been reported, 4,8-11 with one of them predicting the relaxation frequency enhancement. 4 In this letter, we report experimental results and theoretical cal culations of RIN spectra of an injection-locked Fabry-Pérot �FP� laser, and show very good agreement between the theory and experiment. We also compare the RIN spectra of the free-running laser with the injection-locked laser and show an increase of relaxation frequency from 4.5 GHz �free running� to 12 GHz �injection locked�.The experimental setup is shown in Fig. 1. The injection signal from a single-mode distributed-feedback �DFB� mas ter laser passes through an erbium-doped fiber-optical ampli fier �EDFA�. The EDFA is used to amplify the pump DFB laser power and control its injection power into the slave laser over a range up to a few milliwatts. A tunable 3-nm a� Electronic mail: s-chuang@uiuc.edu bandwidth optical filter is used to remove excess signals on the side modes. The injection level is monitored by an opti cal power meter...

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confidence: 99%

Relative intensity noise characteristics of injection-locked semiconductor lasers

Jin

Chuang

2000

Applied Physics Letters

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“…As was mentioned previously, most of the work in this area to date has been on the laser alone [5][6][7][8]11,12]. There has been no work reported which simulates the full communication system in which external injection is used to linearise the modulation response of the directly modulated laser.…”

Section: I(t) = I 0 + δI S(t) = S 0 + δSmentioning

confidence: 99%

“…conditions the relaxation frequency of the laser may be increased significantly [5][6][7][8][9][10][11][12], and the modulation response at lower frequencies can be made significantly more linear than that without external injection [5,13]. This helps to greatly reduce IMD problems.…”

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confidence: 99%

Overcoming laser diode nonlinearity issues in multi-channel radio-over-fiber systems

Smyth

Kaszubowska

Barry

2004

Optics Communications

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The authors demonstrate how external light injection into a directly modulated laser diode may be used to enhance the performance of a multi-channel radio over fiber system operating at a frequency of 6 GHz. Performance improvements of up to 2dB were achieved by linearisation of the lasers modulation response. To verify the experimental work a simulation of the complete system was carried out using Matlab.Good correlation was observed between experimental and simulated results.

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“…The enhancement of resonance frequency [10] and modulation bandwidth [5], [11], [18]- [21] becomes significant. This enhancement has been predicted theoretically, based on rate equation simulations [10].…”

Section: Introductionmentioning

confidence: 99%

Optical Properties and Modulation Characteristics of Ultra-Strong Injection-Locked Distributed Feedback Lasers

Sung

Lau

2007

IEEE J. Select. Topics Quantum Electron.

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Abstract-The optical properties and the frequency responses of ultrastrong (injection ratio > 10 dB) injection-locked distributed feedback lasers are investigated experimentally and theoretically. We have observed three distinctive modulation regimes under different frequency detuning between the master and the slave lasers. At large negative frequency detuning, the laser exhibits enhanced modulation efficiency at low frequencies. At intermediate frequency detuning, a flat frequency response with large 3 dB bandwidth is observed. At large positive frequency detuning, the modulation response shows a pronounced resonance peak at high frequencies. These phenomena can be explained by the resonance enhancement of the slave laser cavity mode, with the resonance frequency equal to the difference between the injection-locked frequency and the cavity mode. The experimental results agree well with theoretical calculations based on three coupled rate equations. Depending on the applications, the injection locking conditions can be optimized to achieve high RF link gain, broadband, or high resonance frequency operations.

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Enhancement of modulation bandwidth of laser diodes by injection locking

Cited by 113 publications

References 7 publications

Relative intensity noise characteristics of injection-locked semiconductor lasers

Relative intensity noise characteristics of injection-locked semiconductor lasers

Overcoming laser diode nonlinearity issues in multi-channel radio-over-fiber systems

Optical Properties and Modulation Characteristics of Ultra-Strong Injection-Locked Distributed Feedback Lasers

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