Single-frequency Output Power Research Articles

500 mW coherent large aperture ring oscillators

A large aperture ring laser having a diffraction limited output measuring 0.2°×0.2° is described. The design uses angled incidence onto monolithic gratings for feedback and mode selectivity. Devices of this design have exhibited threshold current density less than 300 A/cm2 and over 500 mW of single frequency output power.

Monolithic integrated Nd:YAG laser

By application of the technique of optical contact, a novel type of frequency-stable solid-state laser resonator has been developed. A diode-laser-pumped, monolithic integrated twisted-mode-cavity Nd:YAG laser with 80 mW of single-frequency output power at lambda = 1.06 microm has been fabricated. A linewidth below 10 kHz has been measured for the free-running laser.

Towards a coherent optical free-space communication system

A coherent optical communication system based on a diode laser pumped Nd : YAG laser with 620 mW single frequency output power has been developed. Differential phase shift keying at a data rate of 565 Mbit/s has been applied. Biterror-rates of 10−9 have been measured at a received light power of −46 dBm.

Single-frequency operation in solid-state laser materials with short absorption depths

Single-frequency output power of 35 mW has been observed in 3.0% doped Nd:YVO/sub 4/ pumped with a 200-mW laser diode. The single-frequency operation is due to the spatial overlap of longitudinal modes at the surface of a mirror in the laser cavity where the material is pumped. The strong absorption coefficient at 808.7 nm and narrow bandwidth of the Nd:YVO/sub 4/ only allow a single laser mode to operate. The effect is modeled theoretically and compared with the experiment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Radiative characteristics of injection lasers with short resonators

An investigation was made of the threshold, power, and spectral characteristics of radiation emitted by GaAs--AlAs heterostructure injection lasers with double confinement and short (up to 16 ..mu..) plane-parallel resonators. The lasers had mesastripe contacts 10--14 ..mu.. wide. The gain coefficient was a linear function of the pump current density in the gain coefficient range 10--400 cm/sup -1/. The minimum threshold currents in the lasers were 27--30 mA and single-frequency lasing regime was observed right up to pump currents of (1.6--1.7)I/sub th/. The maximum single-frequency output power was 35 mW. It should be possible to retain single-frequency regime in such lasers when the pump current was subjected to high-frequency modulation.

SINGLE-MODE POWER FROM A 6328 Å LASER INCORPORATING NEON ABSORPTION

Strong mode-coupling was induced in a long 6328-Å He–Ne laser by the addition of a separate cell containing excited Ne. The resulting single-frequency output power represented most of the total multimode power available. The laser maintained the same mode of oscillation when tuned throughout the entire gain band. This scheme has produced 9.5 mV at a single frequency and was apparently free from any inherent power limitation.

Stabilized, single-frequency output from a long laser cavity

The problem of obtaining single-frequency output from a long laser is considered, and two methods are investigated experimentally. The first method consists of using an external filter to select one of a number of oscillating modes. The second method consists of suppressing internally the unwanted resonances so that the laser oscillation can only take place at a single frequency. It is shown that with the second method one can in many cases obtain greater power, and experiments are reported in which single-frequency output power of 15 mW was obtained from a 6328 Å He-Ne laser, A simple feedback circuit is described for stabilizing the frequency of the laser oscillation.

Load-rating theory for multichannel amplifiers

The amplifiers of multichannel telephone systems must be so designed with regard to output capacity that interchannel interference caused by amplifier overloading will not be serious. Probability theory is applied to this problem to determine the maximum single-frequency output power which a multichannel amplifier should be designed to transmit as a function of N, the number of channels in the system. The theory is developed to include the effects of statistical variations in the number of simultaneous talkers, in the talking volumes, and in the instantaneous voltages from speech at constant volume.

Load-Rating Theory for Multichannel Amplifiers

The amplifiers of multichannel telephone systems must be so designed with regard to output capacity that interchannel interference caused by amplifier overloading will not be serious. Probability theory is applied to this problem to determine the maximum single-frequency output power which a multichannel amplifier should be designed to transmit as a function of N, the number of channels in the system. The theory is developed to include the effects of statistical variations in the number of simultaneous talkers, in the talking volumes, and in the instantaneous voltages from speech at constant volume.

Load Rating Theory for Multi-Channel Amplifiers*

The amplifiers of multi-channel telephone systems must be so designed with regard to output capacity that interchannel interference caused by amplifier overloading will not be serious. Probability theory is applied to this problem to determine the maximum single frequency output power which a multi-channel amplifier should be designed to transmit as a function of N, the number of channels in the system. The theory is developed to include the effects of statistical variations in the number of simultaneous talkers, in the talking volumes, and in the instantaneous voltages from speech at constant volume.