Ultrafast Zn-Diffusion and Oxide-Relief 940 nm Vertical-Cavity Surface-Emitting Lasers under High-Temperature Operation

Cheng, Chen-Lung; Khan, Zuhaib; Yen, Jia-Liang; Ledentsov, N. N.; Shi, Jin‐Wei

doi:10.1109/jstqe.2019.2921385

Cited by 9 publications

(14 citation statements)

References 17 publications

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“…In the simulation we used the value of ϕ = 3.6 μm. Another important parameter is the Auger recombination coefficient C in equation (5). Its actual value can depend on, for instance, the parameters of the QWs, so there is no universally correct value of this parameter.…”

Section: Results and Comparison With Experimentsmentioning

confidence: 99%

Numerical model for small-signal modulation response in vertical-cavity surface-emitting lasers

Wasiak

Śpiewak

Haghighi

et al. 2020

J. Phys. D: Appl. Phys.

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We present a numerical model allowing for simulations of small-signal modulation (SSM) response of vertical-cavity surface-emitting lasers (VCSELs). The model of SSM response utilizes only the data provided by a static model of continuous-wave operation for a given bias voltage. Thus the fitting of dynamic measurement parameters is not needed nor used. The validity of this model has been verified by comparing experimental SSM characteristics of a VCSEL with the results of simulations. A good agreement between experiment and simulations has been observed. Based on the results obtained in the simulations of the existing laser, the impact of the number of quantum wells in the active region on the modulation properties has been calculated and analyzed.

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Section: Results and Comparison With Experimentsmentioning

confidence: 99%

Numerical model for small-signal modulation response in vertical-cavity surface-emitting lasers

Wasiak

Śpiewak

Haghighi

et al. 2020

J. Phys. D: Appl. Phys.

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“…Figures 10 (a) to (c) show the measured bias dependent E-O frequency responses of a single reference VCSEL unit, array A and array B, respectively, for different oxide aperture sizes (Wo: 11 µm, 14µm). Thanks to the Zn-diffusion and oxide-relief processes, which can effectively release the RC-limited bandwidth of the VCSEL array [25,26], the measured 3-dB E-O bandwidth of array A with a Wo of 14 µm is quite close to that of the single reference VCSEL (~11 vs. 12 GHz) under the same average bias current (~8 mA). Moreover, we can clearly see that, in contrast to array B, which has a low-frequency roll-off of around 4 dB due to the spatial hole burning (SHB) effect [17][18][19] this roll-off has been completely eliminated in the measured E-O responses of array A.…”

Section: Measurement Resultsmentioning

confidence: 99%

“…Here, the crisscross mesas in array A may be treated as optical waveguides that connect different active VCSEL units [22,24] and are highlighted in these two pictures. Figure 1 (b) shows conceptual crosssectional views of the active light-emitting mesa and passive waveguides in array A. Zn-diffusion and oxide-relief processes have been performed on each of the active VCSEL units aimed at manipulating the optical transverse modes and relaxing the RC-limited bandwidth of the array [25,26], respectively. The passive waveguides between the different active mesas are composed of an epi-layer structure in the VCSEL cavity [22,23].…”

Section: Device Structure and Fabricationmentioning

confidence: 99%

“…Based on the measured Bragg wavelength (~853 nm) of the VCSEL cavity, the corresponding cavity-to-PL detuning wavelength is around 15 nm. Such a design can not only improve the high-temperature performance of the VCSEL [26] but also ensure the transparency of our passive waveguide for the propagation of lasing light with a central wavelength at around 850 nm. Optical confinement in the direction perpendicular to the wafer surface of the passive waveguide is achieved by the index contrast between the III-V active multiple quantum wells (MQWs) and the thin (~25 nm) air layer, which is realized by the oxide-relief process, as discussed above.…”

Section: Device Structure and Fabricationmentioning

confidence: 99%

“…In addition, an electroplating process is performed to integrate an additional copper substrate on the backside of our array. In each single VCSEL unit in the array, Zn-diffusion and oxiderelief structures are adopted to obtain the high-brightness (single-mode) output and relax the RC-limited bandwidth [25,26]. This array exhibits improvements in performance in terms of a higher (quasi-) SM output power, narrower divergence angle, lower RIN, and better quality of eye-opening for high-speed data transmission when compared to its traditional counterparts without connections between neighboring active mesas or the copper substrate.…”

Section: Introductionmentioning

confidence: 99%

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High-Brightness, High-Speed, and Low-Noise VCSEL Arrays for Optical Wireless Communication

Khan

Chang

Pan³

et al. 2022

IEEE Access

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The development of high-speed and high-brightness vertical-cavity surface-emitting lasers (VCSELs), which can serve as an efficient light source for optical wireless communication (OWC), play a crucial role in growth of the next generation of wireless communication networks, e.g., 6 G and satellite communications. In this work, by optimizing the size of the Zn-diffusion and oxide-relief apertures in a high-speed 850 nm VCSEL, we obtain record-high brightness (2.9 MWcm sr at 10 mW output) with single polarized and (quasi-) single-mode (SM) outputs under continuous wave (CW) operation. However, such high brightness output comes at the cost of spatial hole burning (SHB) effect and degraded quality of 25 Gbit/sec eye patterns. In addition, an SM VSCEL array structure is usually needed to further boost the total available optical power for long-reach OWC. Here, a novel (quasi-) SM VCSEL array structure is demonstrated which releases the trade-off between the performances of brightness and eye-pattern quality.Our demonstrated array has a special crisscross mesa connecting neighboring VCSEL units and an extra electroplated copper substrate integrated on the backside of the chip. Compared to the reference array without the copper substrate and connected active mesas, the demonstrated array exhibits a higher (quasi-) SM output power, narrower divergence angle, larger orthogonal polarization mode suppression ratio (OPSR), and flatter E-O response. This in turn leads to smaller jitter and less noise in the measured 12.5 Gbit/sec eye-patterns. The demonstrated 7x7 array exhibits a maximum SM power of around 90 mW with a 1/e 2 divergence angle as narrow as 7 o (FWHM: 5 o ), single polarized output (10 dB OPSR), decent relative intensity noise performance (< -130 dB/Hz) and clear 12.5 Gbit/sec eye-opening. Such new device with remarkable static/dynamic performances has strong potential to further improve the product of the linking distance and data rate in the next generation of OWC channels.

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Single‐Mode, High‐Brightness, and High‐Speed VCSEL Arrays

Khan

Shi

2021

Digital Encyclopedia of Applied Physics

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Optical sources such as high‐brightness and high‐speed vertical‐cavity surface‐emitting laser (VCSEL) arrays are preferred for a variety of applications such as, LiDAR, 3‐D sensing, and free‐space optical communication (FSC). However, further improvement in depth of resolution and ranging distance for these time‐of‐flight (ToF)‐driven systems can be accomplished by using VCSEL arrays having high brightness (large output power and narrow divergence angle) and faster response time. However, to increase the output power of these VCSEL arrays to watt level, several light emission apertures (several hundreds) need to be connected in parallel, which results in large parasitic capacitance. Hence, RC‐limited bandwidth becomes an influential aspect that restricts the speed of these high‐power VCSEL arrays. In this review article, we discuss recent progresses in high‐power VCSEL arrays and our own achievements in this field. By using tensile strain (induced by electroplated copper substrate) and Zn‐diffusion technique, we elaborate our previous work in which we successfully demonstrated a novel VCSEL array having high power (3 W), highly single mode (SM), high brightness (1 e−2divergence angle, ∼10°), and single‐polarized output performance without increasing threshold current (Ith) and intra‐cavity loss. Furthermore, thanks to the oxide‐relief process, which has tendency to decrease the parasitic capacitance that leads to rise time of demonstrated VCSEL array as short as around 100 ps. This number is around ten times shorter than that of commercially available VCSEL arrays with the same output power level (∼3 W) at the same wavelength (∼940 nm).

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Ultrafast Zn-Diffusion and Oxide-Relief 940 nm Vertical-Cavity Surface-Emitting Lasers under High-Temperature Operation

Cited by 9 publications

References 17 publications

Numerical model for small-signal modulation response in vertical-cavity surface-emitting lasers

Numerical model for small-signal modulation response in vertical-cavity surface-emitting lasers

High-Brightness, High-Speed, and Low-Noise VCSEL Arrays for Optical Wireless Communication

Single‐Mode, High‐Brightness, and High‐Speed VCSEL Arrays

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