Abstract:In this paper, we present a 1050 nm electrically-pumped micro-electro-mechanically-tunable vertical-cavity-surface-emitting-laser (MEMS-VCSEL) with a record dynamic tuning bandwidth of 63.8 nm, suitable for swept source optical coherence tomography (SS-OCT) imaging. These devices provide reduced cost & complexity relative to previously demonstrated optically pumped devices by obviating the need for a pump laser and associated hardware. We demonstrate ophthalmic SS-OCT imaging with the electrically-pumped MEMS-… Show more
“…For applications that require few milliwatts sent to the sample arm, such as in ophthalmology, a system based on the EI detector can utilize a single VCSEL where almost all of the VCSEL power could be directed to the sample arm using a 99/1 coupler. Our models predict that sensitivities of better than −100 dB could be obtained, using a single micro-scale electrically pumped VCSEL 29, 30 and eliminating the need for optical power amplification. Such a system has also a smaller footprint, lower cost and complexity, as it would eliminate the need for utilizing two channels that require near-perfect matching with regard to the optical signals on each detector in different polarization, gain, and noise across the whole optical bandwidth 17, 21, 22 .Figure 5Schematic of a compact OCT system utilizing the electron-injection detector.
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Optical coherence tomography (OCT) has been utilized in a rapidly growing number of clinical and scientific applications. In particular, swept source OCT (SS-OCT) has attracted many attentions due to its excellent performance. So far however, the limitations of existing photon detectors have prevented achieving shot-noise-limited sensitivity without using balanced-detection scheme in SS-OCT, even when superconducting single-photon detectors were used. Unfortunately, balanced-detection increases OCT system size and cost, as it requires many additional components to boost the laser power and maintain near ideal balanced performance across the whole optical bandwidth. Here we show for the first time that a photon detector is capable of achieving shot noise limited performance without using the balanced-detection technique in SS-OCT. We built a system using a so-called electron-injection photodetector, with a cutoff-wavelength of 1700 nm. Our system achieves a shot-noise-limited sensitivity of about −105 dB at a reference laser power of ~350 nW, which is more than 30 times lower laser power compared with the best-reported results. The high sensitivity of the electron-injection detector allows utilization of micron-scale tunable laser sources (e.g. VCSEL) and eliminates the need for fiber amplifiers and highly precise couplers, which are an essential part of the conventional SS-OCT systems.
“…For applications that require few milliwatts sent to the sample arm, such as in ophthalmology, a system based on the EI detector can utilize a single VCSEL where almost all of the VCSEL power could be directed to the sample arm using a 99/1 coupler. Our models predict that sensitivities of better than −100 dB could be obtained, using a single micro-scale electrically pumped VCSEL 29, 30 and eliminating the need for optical power amplification. Such a system has also a smaller footprint, lower cost and complexity, as it would eliminate the need for utilizing two channels that require near-perfect matching with regard to the optical signals on each detector in different polarization, gain, and noise across the whole optical bandwidth 17, 21, 22 .Figure 5Schematic of a compact OCT system utilizing the electron-injection detector.
…”
Optical coherence tomography (OCT) has been utilized in a rapidly growing number of clinical and scientific applications. In particular, swept source OCT (SS-OCT) has attracted many attentions due to its excellent performance. So far however, the limitations of existing photon detectors have prevented achieving shot-noise-limited sensitivity without using balanced-detection scheme in SS-OCT, even when superconducting single-photon detectors were used. Unfortunately, balanced-detection increases OCT system size and cost, as it requires many additional components to boost the laser power and maintain near ideal balanced performance across the whole optical bandwidth. Here we show for the first time that a photon detector is capable of achieving shot noise limited performance without using the balanced-detection technique in SS-OCT. We built a system using a so-called electron-injection photodetector, with a cutoff-wavelength of 1700 nm. Our system achieves a shot-noise-limited sensitivity of about −105 dB at a reference laser power of ~350 nW, which is more than 30 times lower laser power compared with the best-reported results. The high sensitivity of the electron-injection detector allows utilization of micron-scale tunable laser sources (e.g. VCSEL) and eliminates the need for fiber amplifiers and highly precise couplers, which are an essential part of the conventional SS-OCT systems.
Optical coherence tomography (OCT) is a powerful three-dimensional (3D) imaging modality with micrometer-scale axial resolution and up to multi-GigaVoxel/s imaging speed. However, the imaging range of high-speed OCT has been limited. Here, we report 3D OCT over cubic meter volumes using a long coherence length, 1310 nm vertical-cavity surface-emitting laser and silicon photonic integrated circuit dual-quadrature receiver technology combined with enhanced signal processing. We achieved 15 µm depth resolution for tomographic imaging at a 100 kHz axial scan rate over a 1.5 m range. We show 3D macroscopic imaging examples of a human mannequin, bicycle, machine shop gauge blocks, and a human skull/brain model. High-bandwidth, meter-range OCT demonstrates new capabilities that promise to enable a wide range of biomedical, scientific, industrial, and research applications.
“…Typical short cavity swept sources consist of a broadband gain medium, a wavelength-selection filter, and an optical coupler (OC) used as feedback and output. While the performance of these kinds of swept sources is limited by the cavity length [4], one way to overcome this problem is to shorten the cavity length; micro-electromechanical systems (MEMS) technology has been used on swept sources, including MEMS Fabry-Perot tunable filters, MEMS mirrors with grating filters, and MEMS vertical-cavity surface-emitting lasers (VCSELs) [5][6][7]. Another way is a swept source based on Fourier domain mode locking (FDML) technology, by introducing a several-kilometer single-mode fiber (SMF) in the cavity, meanwhile periodically driving the optical bandpass filter synchronously with the optical round-trip time of the light [8].…”
In this work, we investigate the methods to improve the performance of the swept source at 1.0 μm based on a polygon scanner, including in-cavity parameters and booster structures out of the cavity. The three in-cavity parameters are the cavity length, the rotating speed of the polygon scanner, and the in-cavity energy. With the decrease of cavity length, the spectrum bandwidth becomes wider and the duty cycle becomes higher. With the increase of the rotating speed of the polygon, the spectrum bandwidth becomes narrower, and the duty cycle becomes lower but the repetition rate becomes higher. With more energy in-cavity, the spectrum bandwidth becomes wider and the duty cycle becomes higher. The booster structures include the buffered structure, secondary amplifier, and dual-semiconductor optical amplifier configuration, which are used to increase the sweep frequency to 86 kHz, the output power to 18 mW, and the tuning bandwidth to 131 nm, respectively.
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