Coherently coupled laser arrays for low-dispersion, ultra-high-bandwidth data transfer

Fryslie, Stewart T. M.; Choquette, Kent D.

doi:10.1117/2.1201505.005958

Cited by 3 publications

(1 citation statement)

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“…An interesting discovery is that modulation bandwidth may be appreciably improved with coherently coupled arrays [1,2]. Recently we reported the ability to tune 2x1 phased, photonic crystal VCSEL arrays into various regions of coherently coupled operation [3] and its utilization for producing greatly enhanced resonance frequency and modulation bandwidth [2,4]. We have since applied dynamic coupled mode theory to evaluate relevant aspects of modulation response and locking range dynamics observed from coherently coupled 2x1 arrays.…”

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Analysis of modulation response and locking range dynamics for coherently coupled phased, vertical cavity laser arrays

Fryslie

Choquette

2015

2015 IEEE Photonics Conference (IPC)

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High-speed vertical-cavity surface-emitting lasers (VCSELs) are important for optical data transmission applications. Modulation bandwidth for free-running VCSELs typically ranges from few to twenty GHz. An interesting discovery is that modulation bandwidth may be appreciably improved with coherently coupled arrays [1,2]. Recently we reported the ability to tune 2x1 phased, photonic crystal VCSEL arrays into various regions of coherently coupled operation [3] and its utilization for producing greatly enhanced resonance frequency and modulation bandwidth [2,4]. We have since applied dynamic coupled mode theory to evaluate relevant aspects of modulation response and locking range dynamics observed from coherently coupled 2x1 arrays.As depicted in Fig. 1, the two gain regions of the 2x1 phased, photonic crystal VCSEL array are defined by ion implantation while the cavities are defined by the photonic crystal hole pattern [5]. This structure enables strong optical coupling between array elements and stable coherently coupled operation under proper bias conditions. As indicated, the DC bias currents I 1 and I 2 are applied independently to elements 1 (E1) and 2 (E2), respectively. By changing the injection bias conditions, we can tune the resonance of each element and thus the phase relation and coherence of the array [6,7]. The data shown in Figs. 2 and 3 were obtained from a 2x1 array.By considering the resonance detuning and phase shift between coherently coupled elements, we can extract parameters for dynamic coupled mode theory analysis. The spectral data for intensity and wavelength of emission vs. bias current I 2 with a constant bias I 1 = 4.8mA is shown by Fig. 2. The locking range (operation conditions over which the natural resonances of individual array elements become locked in a coherently coupled mode) has been indicated. Furthermore, for brevity the low and high I 2 bias ends of the locking range will be referred to as the lowend locking range (LELR) and high-end locking range (HELR), respectively, as indicated in Fig. 2. Information about the resonance detuning can be extracted from this spectral data. As shown, the resonance wavelength detuning !" m = " m -" coupled of each element m is tuned from !" 1 # +0.1nm for E1 and !" 2 # -0.01nm for E2 at the LELR to !" 1 # !" 2 # 0nm at the HELR. The inset in Fig. 2 shows a measured far-field intensity profile from the coherently coupled array. By propagating the near-field apertures to the far-field via the Fraunhofer approximation (not shown here), we are able to match the behavior of the experimentally determined far-field intensity profile and, in doing so, extract the coupling phase between elements [6,7]. For this array, a coupling phase of $ # % was determined.In order to engineer an array for the desired behavior of a particular application, it is important to understand the theory that governs its dynamics. Dynamic coupled mode theory is highly developed and has been successfully applied to coupled and injection-locked VCSEL arrays [8]. The time cha...

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