The existing optical cryptosystems always process the plaintexts into a random noise image, and the length of the key in the encryption progress is generally much longer than that of the plaintext. In this work, a Harr-wavelet-based optical cryptosystem using the convex lens is proposed. This scheme only needs recording the amplitude. The encryption key includes a series of parameters which is quite shorter than the length of the plaintext. These keys are natural inherent parameters. The Harr transform is introduced to improve the sensibilities of encryption keys and reduce the length of the ciphertexts. The ciphertext is a diffraction-pattern-like image which contains no information of plaintext. Besides, the cost of the whole optical encryption is reduced heavily. Extensive numerical simulations are carried out to verify the security, feasibility, and sensibilities of encryption keys of the proposed encryption scheme. In addition, how to properly select encryption keys is also discussed.
Room-temperature cascaded mid-infrared (MIR) pulsed laser output in Er:YAG crystal is reported. The 1469nm characteristic wavelength of the cascade emission is observed. The characteristic wavelength of the excited-state absorption (ESA) is determined as 1676nm. An Er:YAG crystal with concentration of 10at.% is adopted to compare the laser output energy in the cascaded and non-cascaded configuration. The maximum single pulse energy of MIR laser increases from 1.04mJ (non-cascade) to 1.51mJ (cascade), corresponding to a ratio of 45.2%. The “cyclic cascade” is considered to be the mechanism responsible for the laser performance optimization. The experimental results confirm the existance of cascade at room temperature in Er:YAG crystal. Moreover, cascade is helpful to improve the single pulse energy of MIR laser.
We present a novel structure of planar waveguide for Yb:YAG laser amplifiers allowing large absorption length. The structure parameters of the planar waveguide were optimized using an 3D amplification model. The performance of the optimized planar waveguide laser amplifier was simulated, and a comparison between the cases with and without considering pump saturation was carried out. The simulated results show that a high pump absorption efficiency and optical-to-optical efficiency can be expected in addition to a good absorption uniformity. The seeder power is scaled from 200W to 7000W, the corresponding pump absorption and optical-to-optical efficiencies are 98.6% and 68%, respectively. The thermal stress of the designed planar waveguide is analyzed theoretically, the results show that the pump power of 10kW is available without the fracture risk.
We present a novel structure of planar waveguide for Yb:YAG laser amplifiers allowing large absorption length. The structure parameters of the planar waveguide were optimized using an 3D amplification model. The performance of the optimized planar waveguide laser amplifier was simulated, and a comparison between the cases with and without considering pump saturation was carried out. The simulated results show that a high pump absorption efficiency and optical-to-optical efficiency can be expected in addition to a good absorption uniformity. The seeder power is scaled from 200W to 7000W, the corresponding pump absorption and optical-to-optical efficiencies are 98.6% and 68%, respectively. The thermal stress of the designed planar waveguide was analyzed theoretically, showing that the pump power of 10kW is available according to the stress fracture limit.
Room-temperature cascaded mid-infrared (MIR) pulsed laser output in Er:YAG crystal is reported. The 1469nm characteristic wavelength of the cascade emission is observed. The characteristic wavelength of the excited-state absorption (ESA) is determined as 1676nm. An Er:YAG crystal with concentration of 10at.% is adopted to compare the laser output energy in the cascaded and non-cascaded configuration. The maximum single pulse energy of MIR laser increases from 1.04mJ (non-cascade) to 1.51mJ (cascade), corresponding to a ratio of 45.2%. The “cyclic cascade” is considered to be the mechanism responsible for the laser performance optimization. The experimental results confirm the existance of cascade at room temperature in Er:YAG crystal. Moreover, cascade is helpful to improve the single pulse energy of MIR laser.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.