Theory and experiment of In/sub 1-x/Ga/sub x/As/sub y/P/sub 1-y/ and In/sub 1-x-y/Ga/sub x/Al/sub y/As long-wavelength strained quantum-well lasers

IEEE J. Quantum Electron.

et al. 1999

Self Cite

Abstract-We present theory and experiment for high-speed optical injection in the absorption region of a quantum-well laser and compare the results with those of the electrical injection in cluding carrier transport effect. We show that the main difference between the two responses is the low-frequency roll-off. By using both injection methods, we obtain more accurate and consistent measurements of many important dynamic laser parameters, which include the differential gain, carrier lifetime, � factor, and gain compression factor. Temperature-dependent data of the test laser are presented which show that the most dominant effect is the linear degradation of differential gain and injection efficiency with increasing temperature. While the �-factor is insensitive to temperature variation for multiple-quantum-well lasers, we find that the carrier capture time and nonlinear gain suppression coefficient decreases as temperature increases.

Section: Temperature Dependencementioning

confidence: 99%

Temperature dependence of electrical and optical modulation responses of quantum-well lasers

Keating

IEEE J. Quantum Electron.

et al. 1999

Self Cite

“…Our model also takes into account the master laser frequency noise, intensity noise, and the optical con finement factor of the QW laser structure. 12 The gain satura tion, which is expressed as G(n)�G 0 /(1�� 0 S 0 �� i S i ), is also included, where � 0 and � i are the nonlinear gain satura tion coefficients corresponding to the slave laser signal and the injected signal. The rate equations for the slave laser field…”

mentioning

confidence: 99%

Relative intensity noise characteristics of injection-locked semiconductor lasers

Applied Physics Letters

2000

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...

“…5 are the theoretical calculations, which agree very well with our ex perimental data. In our calculation, some of the parameters such as the effective index of refraction, intrinsic loss, and the initial value of the differential gain are obtained from previous inde pendent measurements [27]. The effective index of refraction of the test laser is , which can be used to calculate the group velocity cm/s, the facet re flection coefficient , mirror loss cm , and photon lifetime ps.…”

Section: Small-signal Xgmmentioning

confidence: 99%

“…The composition of the undoped active region is described in Table II. The barrier photoluminescence wavelength is 1.21 m, and the photoluminescence wavelength peak of the active region is 1.56 m. We select a pump laser wavelength around 1.542 m, which is in the gain region of the test laser [27].…”

Section: A Experimental Setupmentioning

confidence: 99%

Theory and experiment of high-speed cross-gain modulation in semiconductor lasers

Keating

IEEE J. Quantum Electron.

2000

Self Cite

Abstract-We present theory and experiment for the high-speed modulation response of a quantum-well (QW) laser in the pres ence of an external microwave modulated optical pump in the gain region. The model includes the effects of pump-induced stimulated recombination and cross-gain saturation. Expressions for the small-signal modulation response of the test laser under gain modulation are derived. We also present experimental results using a multiple-QW InGaAlAs Fabry-Perot (FP) laser at 1.552 m as the test laser and an external pump by a 1.542 m DFB laser. Comparison between electrical modulation and optical cross-gain modulation (XGM) of the test laser is also presented, which shows improvement of the modulation bandwidth by optical XGM. Our data show a reduction of carrier lifetime with increasing optical pumping, a shift of the test-laser threshold current, a change in the K factor, and a variation of the relaxation frequency with different pump powers. The experimental results agree very well with the theoretical results.