Standard Vertical-cavity Surface-emitting Lasers Research Articles

Label-free integrated microfluidic plasmonic biosensor from vertical-cavity surface-emitting lasers for SARS-CoV-2 receptor binding domain protein detection.

The nanoplasmonic sensor of the nanograting array has a remarkable ability in label-free and rapid biological detection. The integration of the nanograting array with the standard vertical-cavity surface-emitting lasers (VCSEL) platform can achieve a compact and powerful solution to provide on-chip light sources for biosensing applications. Here, a high sensitivity and label-free integrated VCSELs sensor was developed as a suitable analysis technique for COVID-19 specific receptor binding domain (RBD) protein. The gold nanograting array is integrated on VCSELs to realize the integrated microfluidic plasmonic biosensor of on-chip biosensing. The 850 nm VCSELs are used as a light source to excite the localized surface plasmon resonance (LSPR) effect of the gold nanograting array to detect the concentration of attachments. The refractive index sensitivity of the sensor is 2.99 × 106 nW/RIU. The aptamer of RBD was modified on the surface of the gold nanograting to detect the RBD protein successfully. The biosensor has high sensitivity and a wide detection range of 0.50 ng/mL - 50 µg/mL. This VCSELs biosensor provides an integrated, portable, and miniaturized idea for biomarker detection.

Metasurface Enabled On-Chip Generation and Manipulation of Vector Beams from Vertical Cavity Surface-Emitting Lasers.

Metasurface polarization optics that consist of 2D array of birefringent nano-antennas have proven remarkable capabilities to generate and manipulate vectorial fields with subwavelength resolution and high efficiency. Integrating this new type of metasurface with the standard vertical cavity surface-emitting laser (VCSEL) platform enables an ultracompact and powerful solution to control both phase and polarization properties of the laser on a chip, which allows to structure a VCSEL into vector beams with on-demand wavefronts. Here, this concept is demonstrated by directly generating versatile vector beams from commercially available VCSELs through on-chip integration of high-index dielectric metasurfaces. Experimentally, the versatility of the approach for the development of vectorial VCSELs are validated by implementing a variety of functionalities, including directional emission of multibeam with specified polarizations, vectorial holographic display, and vector vortex beams generations. Notably, the proposed vectorial VCSELs integrated with a single layer of beam shaping metasurface bypass the requirements of multiple cascaded optical components, and thus have the potential to promote the advancements of ultracompact, lightweight, and scalable vector beams sources, enriching and expanding the applications of VCSELs in optical communications, laser manipulation and processing, information encryption, and quantum optics.

A GaN‐Based VCSEL with a Convex Structure for Optical Guiding

In this paper, room‐temperature continuous‐wave operation of a GaN‐based vertical‐cavity surface‐emitting laser (VCSEL) with a convex structure for optical guiding is demonstrated. The GaN‐based VCSEL is designed and fabricated with the convex structure containing a 15‐nm step between the center area and the peripheral area of the VCSEL with a Nb2O5 spacer layer. In theory the convex structure with a 1.5% relative refractive index difference between the areas could provide more than 10 high‐order modes. Experimental emission spectra and near field pattern images clearly suggested a multi‐mode operation of the VCSEL with the convex structure. In addition, the VCSEL shows a lower threshold current, 2 mA, and a higher maximum light output power, 0.88 mW, which are superior to those of our standard VCSEL fabricated simultaneously without the convex structure. These results indicate that the optical guiding with the convex structure plays an important role in developments of GaN‐based VCSELs.

Oxide-confined VCSELs fabricated with a simple self-aligned process flow

We propose a simplified and easier fabrication process flow for the manufacturing of AlOx-confined vertical-cavity surface-emitting lasers (VCSELs) based on combining the oxidation step with a self-aligned process, allowing the mesa etching and two successive lift-off steps based on a single lithography step. The electro-optical confinement achieved by standard lateral oxidation enables a low threshold and a single mode behavior for the VCSEL. This simplified process can largely improve VCSEL manufacturing by reducing the processing time and costs compared to the standard VCSEL process.

Single mode vertical-cavity surface emitting laser with surface plasmon nanostructure

The vertical-cavity surface-emitting laser（VCSEL） has proved to be a low cost light source with attractive properties such as surface emission, circular and low divergence output beam, and simple integration in two-dimensional array. Many new applications such as in spectroscopy, optical storage, short distance fiber optic interconnects, and in longer distance communication, are continuously arising. Many of these applications require stable and single-mode high output power. Several methods that affect the transverse guiding and/or introduce mode selective loss or gain have been developed. In this study, a method for improving the single mode output power by using metal surface plasmons nanostructure is proposed. Theoretical calculation shows that the outpout power is improved about 50% compared to the result of standard VCSELs.

Stable single-mode operation of VCSELs with a mode selective aperture

We have developed single-mode vertical-cavity surface-emitting laser (VCSELs) with a mode selective aperture (MSA) in the DBR mirror that exhibits a high-order transverse-mode filtering effect. The VCSELs with an MSA were fabricated using standard intracavity-contacted VCSEL processes without any additional steps resulting from the simultaneous formation of the MSA and current aperture via a single-step oxidation. The VCSELs fabricated with a current aperture and MSA diameter of 5 and 7 μm, respectively, exhibited a stable single-mode operation with a side mode suppression ratio of over 35 dB and a divergence angle below 10° for the entire drive current range.

Polarization-Controlled Surface Grating VCSELs Under Externally Induced Anisotropic Strain

The polarization control of surface grating vertical-cavity surface-emitting lasers (VCSELs) is tested under externally applied anisotropic stress and is compared to that of a nominally identical standard VCSEL without a surface grating. This is done by bending the VCSEL chip in a well-defined way. The anisotropic in-plane strain thus induced in the VCSELs leads to a polarization switch of the standard VCSEL for rather moderate strain. In contrast, the polarization of the surface grating VCSELs is fixed by the grating and remains unchanged despite a high strain which causes a wavelength splitting of the two polarization modes of about 130 pm. Such a result is of high practical relevance, since strain is unavoidably induced during VCSEL fabrication and mounting and counteracts any method applied for polarization control.

Polarization-Controlled Surface Grating VCSELs Under Unpolarized and Polarized Optical Feedback

The polarization control of a surface grating vertical-cavity surface-emitting laser (VCSEL) and of a nominally identical standard VCSEL without a surface grating are compared for unpolarized and polarized optical feedback with different feedback levels in the long external cavity regime. While the polarization of the standard VCSEL is strongly influenced by isotropic feedback with a feedback level of just 1% and can even be controlled by polarized feedback, the surface grating VCSEL remains polarization-stable under isotropic feedback. Its polarization can only be disturbed by optical feedback polarized orthogonal to the polarization of the solitary surface grating VCSEL for feedback levels exceeding 18%.

Self-Aligned Microlens-Integrated Vertical-Cavity Surface-Emitting Lasers

A novel method for fabricating microlens-integrated vertical-cavity surface-emitting lasers (VCSELs) by selective oxidation of composition-graded digital alloy AlGaAs was developed. Due to the simultaneous formation of a microlens and oxide aperture via single-step oxidation, self-aligned microlens-integrated VCSELs could be fabricated using standard intracavity-contacted VCSEL processing without additional process steps. The output beam from the oxide-buried and oxide-removed AlGaAs microlens-integrated VCSELs was strongly focused to a beam radius of 3.7 and 3.5 mum at a distance of about 25 and 15mum, respectively, from the surface of the VCSEL

A new approach to improve mode selectivity of higher output oxide-confined vertical-cavity surface-emitting lasers

Requirements of a higher output and the single-fundamental-mode operation are usually contradictory to each other. In the present paper, an essential modification of a design of the GaAs-based oxide-confined vertical-cavity surface-emitting lasers (VCSELs) is proposed. Functions of both the oxide apertures are separated: while the larger upper one is designed to create the radial waveguiding effect, the smaller bottom one is only funnelling the current injection into the active region. Hence both may be optimized separately. As a result, single-fundamental-mode operation is confirmed by our simulation to be preserved at much higher output and/or at much higher temperatures than in standard VCSELs.

Nitride VCSEL design for continuous-wave operation of higher-order optical modes

Anticipated performance of possible designs of nitride vertical-cavity surface-emitting lasers (VCSELs) has been analyzed and compared with the aid of an advanced 3D optical–thermal–electrical self-consistent simulation. It has been revealed in the simulation that, to achieve room-temperature (RT) continuous-wave (CW) VCSEL threshold operation, uniformity of both carrier-concentration and temperature-increase distributions within VCSEL active regions are equally important. Besides, mostly because of problems with an effective confinement of an optical field in a radial direction, RT CW lasing in standard nitride VCSELs is usually easier to achieve on higher-order transverse modes than on lower-order ones. Therefore, a novel design of nitride VCSELs with double (annular and central dot) p-side contacts has been intentionally constructed to enhance an excitation of low-threshold high-order transverse optical modes. Anticipated RT CW performance characteristics of the novel design have been proved to be definitely more promising than those of other possible configurations of nitride VCSELs. In particular, our calculations have confirmed that RT CW lasing is possible in this new nitride VCSEL. Besides, this device has been found to be less sensitive (than other nitride VCSELs) to possible crystal imperfections created around an active region while high-resistive areas are formed.

Optoelectronic device simulation of Bragg reflectors and their influence on surface-emitting laser characteristics

This paper presents a simulation analysis of distributed Bragg reflectors (DBRs) and their affect on the characteristics of vertical-cavity surface-emitting lasers (VCSELs). The SimWindows semiconductor device simulator models the close interaction between electrical, optical, and thermal processes present in VCSELs. This simulator is used to examine the electrical characteristics of some simple DBR designs. Due to the different transport characteristics of electrons and holes, these results will show that n-type DBR designs must be different than p-type designs in order to achieve the best operating characteristics for the overall laser. This analysis will demonstrate the improvement in the characteristics by comparing the simulation results of a standard VCSEL with the results of a VCSEL using improved DBR designs.

Electro-optic birefringence in semiconductor vertical-cavity lasers

Birefringence induced by the electro-optic effect is demonstrated in vertical-cavity surface-emitting lasers (VCSEL). This is done by comparing two types of optically pumped VCSELs: VCSELs with standard pin-doping and VCSELs with symmetrical pip-doping. The observed birefringence in these VCSELs differs by an order of magnitude, a difference that we ascribe to the presence and absence, respectively, of electro-optic birefringence.