共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
A method that uses the quadrant photodiode has been shown to be relatively inexpensive and robust in measuring Gaussian laser beam diameters in two axes. This approach requires neither component rotation nor precision alignment, and it facilitates integration of Gaussian laser beam diameter measurement with laser beam tracking in instruments. The physical gap between sensors in the quadrant photodiode, however, limits laser beam diameter measurements to those in the millimeter range. Here, we describe a modified approach to measure Gaussian laser beam diameters that are significantly smaller. 相似文献
3.
A. D. Lucas 《Optical and Quantum Electronics》1974,6(2):153-160
Preparation of silicon avalanche photodiodes by a planar method in epitaxial PP+ silicon slices limited charge collection to carriers generated in or close to the depletion region. Reducing the effective size of the zero-field absorption region surrounding the depletion region by this method, resulted in the output signal current of the device reproducing the input light pulse shape, within 15 ns. When illuminated with monochromatic radiation, the shot noise of a detector prepared in epitaxial material was less than that observed with a device fabricated in homogeneous material, due to the reduced signal current. 相似文献
4.
5.
P. Chakrabarti S. C. Choudhury B. B. Pal 《Applied Physics A: Materials Science & Processing》1989,48(4):331-334
The noise generated due to randomness of multiplication process in the avalanche region of an Al
x
Ga1–x
As/GaAs quantum well p+-i-n+ structure has been studied. The paper presents a quantitative evaluation of the noise performance of the superlattice APD which has not been done so far. Further, useful design data for low noise structure is given. 相似文献
6.
A superlattice avalanche photodiode using III–V materials is expected to be used in long-distance fiberoptic communication systems in the 1.3 to 1.55 m wavelength range. Theoretical studies have been made on the effective ionization rates of electrons and holes of the device, I–V characteristic and the frequency response characteristic of the Al
x
Ga1–x
As/GaAs superlattice p+-i-n+ structure. It is observed that the/ ratio of the device increases with the field and the bandwidth of the response curve increases with decrease in the dc multiplication gain. 相似文献
7.
Reduction of range walk error in direct detection laser radar using a Geiger mode avalanche photodiode 总被引:3,自引:0,他引:3
In this paper a new technique to improve the accuracy of direct detection time-of-flight (TOF) laser radar using a Geiger mode avalanche photodiode (APD) by reducing range walk error is presented. Assuming that the creation of primary electrons in the APD is Poisson-distributed, a mathematical model for the detection probability of each time bin in a TOF histogram is derived. It is shown that the range walk error depends on the energy of the laser-return pulse at the Geiger mode APD with the mathematical model regarded as the TOF histogram of multiple laser pulses in a single-hit case. The method which reduces the range walk error with the center of mass detection in the TOF histogram is then proposed, and the experiment for its proof is carried out. 相似文献
8.
An autofocus technique is proposed for a three-dimensional imaging, direct-detection laser radar system that uses a Geiger-mode avalanche photodiode focal plane array (GmAPD-FPA). This technique is implemented by pointing laser pulses on a target of interest and observing its scattered photon distribution on a GmAPD-FPA. Measuring the standard deviation of the photon distribution on a GmAPD-FPA enables the best focus condition to be found. The feasibility of this technique is demonstrated experimentally by employing a 1 × 8 pixel GmAPD-FPA. It is shown that the spatial resolution improves when the GmAPD-FPA is located in the best focus position found by the autofocus technique. 相似文献
9.
《Current Applied Physics》2010,10(4):1041-1045
The single pulse detection and false-alarm probability in measuring time of flight (TOF) of laser pulse are caused by the creation of primary electrons in Geiger mode avalanche photodiode (APD). Measuring the detection and false-alarm probabilities with longer laser pulse than time bin and artificial noise source, we have experimentally proved that the creations of primary electrons in Geiger mode APD is Poisson distributed. It is also shown theoretically that there is little difference between smaller and larger laser pulse width than time bin cases on measurements of both detection and false-alarm probability. 相似文献
10.
A multichannel detector has been constructed using a single avalanche photodiode and a fiber-loop delay line. Detection probabilities of the channels can be set using a variable-ratio coupler. The performance of the detector is demonstrated on its capability to distinguish multi-photon states (containing two or more photons) from the one-photon state and the vacuum state.Received: 16 July 2003, Published online: 14 October 2003PACS:
42.50.Dv Nonclassical states of the electromagnetic field, including entangled photon states; quantum state engineering and measurements - 03.67.Hk Quantum communication 相似文献
11.
Žarko P. Barbarić Stojadin M. Manojlović Boban P. Bondžulić Milenko S. Andrić Srđan T. Mitrović 《Optik》2014
New relationship of displacement signal using opposite sectors on a quadrant photodiode is derived. Standard and new displacement signals are analyzed in details. Through MATLAB® laser tracking simulation models, based on common and suggested approaches, detailed analysis is performed, and it is shown that better results for the new relationship signal processing are obtained. Within new relationship of displacement signal, the sensitivity of the system to the displacement of the spot increases and, hence, provides better accuracy in positioning up to 30%. 相似文献
12.
A highly sensitive photodetection system with a detection limit of 1 photon/s was developed. This system uses a commercially available 200-microm-diameter silicon avalanche photodiode (APD) and an in-house-developed ultralow-noise readout circuit, which are both cooled to 77 K. When the APD operates at a low gain of approximately 10, it has a high-linearity response to the number of incident photons and a low excess noise factor. The APD also has a high quantum efficiency and a dark current of less than 1 e/s at 77 K. This photodetection system will shorten measurement time and permit higher spatial and wavelength resolution for near-field scanning optical microscopes. 相似文献
13.
A novel profilometry method based on two-photon absorption in a silicon avalanche photodiode is proposed. This method has a wide dynamic range, from millimeters to tens of meters. The principle is experimentally confirmed with a fiber-optic Mach-Zehnder interferometer. 相似文献
14.
Jianhua Huang Min Ren Yan LiangZhiyuan Wang Xiaomeng WangWeibin Kong E. WuGuang Wu Heping Zeng 《Optik》2014
We experimentally studied photon-counting laser ranging at 1550 nm using InGaAs/InP avalanche photodiode based single-photon detectors (SPDs). The SPDs operated in the passive quenching and 1-GHz sinusoidal gating Geiger modes, corresponding to continuous and quasi-continuous photon-counting ranging, respectively. Despite that the passively quenched SPD provided relatively high effective detection efficiency, quasi-continuous photon-counting ranging excelled the continuous one with fast acquisition speed and improved depth resolution due to the short deadtime and low timing jitter of the SPD in 1-GHz sinusoidally gated mode. 相似文献
15.
The noise performance of an InP/InGaAs Superlattice Avalanche Photodiode (SL-APD) has been studied theoretically to examine its suitability as a detector in optical receiver units. The results indicate that the device which has a very large gain-bandwidth product (450 GHz) provides a high receiver sensitivity compared to conventional APD. The device also exhibits a very low value of excess noise factor which results in a high value of signal-to-noise ratio. The SL-APD is expected to find useful applications as a high sensitivity photodetector in long-haul fibre optic communication systems. For a digital system, the device exhibits a very low value of bit-error rate (BER) even at moderate gain. 相似文献
16.
17.
Yury Vasileuski Sergei Malyshev Alexander Chizh 《Optical and Quantum Electronics》2008,40(14-15):1247-1253
Design and characteristics of the guardring-free planar InGaAs/InP avalanche photodiode are considered based on 2D numerical simulation. The device incorporates n-charge sheet and p-charge sheet, which spatially separates multiplication layer and p+-region. Simulation results of 2D electric field and impact ionization rate profile, current-voltage, capacitance-voltage and bandwidth-gain characteristics are discussed. 相似文献
18.
In this Letter, a new method for avalanche photodiode characterization, based on the spectral analysis of the photocurrent produced during an avalanche, is proposed. The theory is developed, and an experimental characterization of an avalanche photodiode working in the Geiger mode with CW laser is performed. 相似文献
19.
《中国光学快报(英文版)》2016,(3)
Solar-blind ultraviolet detection is of great importance in astronomy and industrial and military applications.Here, we report enhanced solar-blind ultraviolet single-photon detection by a normal silicon avalanche photodiode(Si APD) single-photon detector with a specially designed photon-collecting device. By re-focusing the reflected photon from the Si chip surface on the detection area by the aluminum-coated hemisphere, the detection efficiency of the Si APD at 280 nm can be improved to 4.62%. This system has the potential for high-efficiency photon detection in the solar-blind ultraviolet regime with low noise. 相似文献