High-brightness and high-speed vertical-cavity surface-emitting laser arrays

Abstract

High-power vertical-cavity surface-emitting laser (VCSEL) arrays, which can serve as the light source in modern lidar and three-dimensional optical sensing systems, have recently attracted a lot of attention. In these types of systems, the time-of-flight (ToF) technique, based on the round-trip time of short optical pulses is usually adopted. Further enhancement of the ranging distance and depth resolution in these ToF driven systems by the incorporation of a VCSEL array with a high available power, high brightness (narrow divergence angle), and fast response time is highly desirable. However, a large number of light emission apertures (several hundreds) in the VCSEL array is usually necessary to raise the output power level to several watts. This leads to a large parasitic capacitance and the RC-limited bandwidth may become the dominant limiting factor of the speed of the high-power VCSEL array. In this work, Zn-diffusion and oxide-relief apertures are used to manipulate the optical modes and reduce the parasitic capacitance, respectively, in a unit device for a 940 nm VCSEL array. The demonstrated VCSEL array has a quasi-single-mode output, high available power (4 W; 1% duty cycle), narrow divergence angle ( ∼ 14 ∘ at 1 / e 2 ) under maximum output power, and a fast rise time ( &lt;<!-- 100 p s ). These results open up new possibilities for further enhancing the performance of ToF sensing systems at the 940 nm wavelength.

Electrically Parallel Three-Element 980 nm VCSEL Arrays with Ternary and Binary Bottom DBR Mirror Layers

“…We find that, for free-space optical communication, top-emitting electrically parallel VCSEL arrays with small to medium aperture diameters become increasingly attractive compared to larger-aperture single VCSELs as the required optical output power increases. For large numbers of elements (~570 elements as in [ 28 ] for example), we anticipate significant decreases in bandwidth for top-emitting arrays due to increased resistive and capacitive losses. By neglecting far-field patterns and beam shaping (not investigated here) at low to moderate optical output powers (about 50 mW or less), single VCSELs may suit the application.…”

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

“…However, this approach will reduce the photon lifetime (τp) inside the VCSEL cavity, which in turn leads to a more pronounced relaxation oscillation phenomenon in the measured electrical-to-optical (E-O) frequency responses and higher relative intensity noise (RIN) from the light output of the VCSEL [9,10] which impedes their application for communications. One of the most effective ways to achieve an output beam with a narrow farfield divergence angle is to assemble the VCSEL array from several single-mode (SM) VCSEL units [11,12], which usually have a perfect Gaussian beam output with narrow divergence angle. Various VCSEL structures capable of producing highly SM power have been reported previously including surfacerelief [13], Zn-diffusion [14], photonic crystal [15], and antiguide (leaky) cavity structures [16].…”

High-Speed and High-Power 940 nm Flip-Chip VCSEL Array for LiDAR Application

“…The majority of VCSEL arrays are almost entirely made up of vertical structures [10][11][12]. It is worth mentioning that when the VCSEL is operating at a higher injection current, the thick epitaxial substrate produces an enormous amount of heat and a drop in the PCE; additionally, earlier roll-over behaviors and a lower response speed have been observed [13].…”