公开(公告)号：WO1986000763A1

公开(公告)日：1986-01-30

申请号：PCT/US1985000608

申请日：1985-04-08

Applicant: HUGHES AIRCRAFT COMPANY

Inventor： HUGHES AIRCRAFT COMPANY ,  HALMOS, Maurice, J. ,  HENDERSON, David, M.

IPC: H01S03/137

CPC classification number: H01S3/1398 ,  H01S3/107

Abstract: A chirp laser system includes an intracavity electro-optical crystal which is modulated at a relatively high frequency, for example 250 kilohertz, to sweep the frequency of the transmitter laser above and below its nominal center frequency. One of the mirrors associated with the laser transmitter is adjustable to vary the length of the laser cavity and to thereby shift the frequency of the transmitter laser. When the frequency of the transmitter laser is shifted, the output amplitude of the laser changes to some extent. With the center frequency of the laser at a maximum gain point, the amplitude of the output signals during the positive and negative frequency excursions of the transmitter laser will be substantially symmetrical. However, if thermal or other effects cause the frequency of the laser to shift away from the maximum gain point, the output during positive and negative excursions will be asymmetrical, for example, with the gain dropping off during an upward frequency excursion, and perhaps increasing or not dropping off nearly as much during a low frequency excursion. A small part of the output from the transmitter laser is sampled, and the amplitude during positive and negative frequency shift excursions is compared, using a square wave derived from the chirp modulating driver. Where the detected signals for the positive and negative frequency excursions are substantially equal, no change in the position of the mirror is accomplished; however, when the excursions result in a difference in the amplitude of the detected signals, the position of the piezoelectrically adjustable mirror is shifted to restore the nominal center frequency of the laser to its maximum amplitude point on the gain curve.

公开(公告)号：EP0191769B1

公开(公告)日：1988-11-17

申请号：EP85902234.5

申请日：1985-04-08

Applicant: Hughes Aircraft Company

Inventor： HALMOS, Maurice, J. ,  HENDERSON, David, M.

IPC: H01S3/13

CPC classification number: H01S3/1398 ,  H01S3/107

Abstract: A chirp laser system includes an intracavity electro-optical crystal which is modulated at a relatively high frequency, for example 250 kilohertz, to sweep the frequency of the transmitter laser above and below its nominal center frequency. One of the mirrors associated with the laser transmitter is adjustable to vary the length of the laser cavity and to thereby shift the frequency of the transmitter laser. When the frequency of the transmitter laser is shifted, the output amplitude of the laser changes to some extent. With the center frequency of the laser at a maximum gain point, the amplitude of the output signals during the positive and negative frequency excursions of the transmitter laser will be substantially symmetrical. However, if thermal or other effects cause the frequency of the laser to shift away from the maximum gain point, the output during positive and negative excursions will be asymmetrical, for example, with the gain dropping off during an upward frequency excursion, and perhaps increasing or not dropping off nearly as much during a low frequency excursion. A small part of the output from the transmitter laser is sampled, and the amplitude during positive and negative frequency shift excursions is compared, using a square wave derived from the chirp modulating driver. Where the detected signals for the positive and negative frequency excursions are substantially equal, no change in the position of the mirror is accomplished; however, when the excursions result in a difference in the amplitude of the detected signals, the position of the piezoelectrically adjustable mirror is shifted to restore the nominal center frequency of the laser to its maximum amplitude point on the gain curve.

公开(公告)号：EP0191769A1

公开(公告)日：1986-08-27

申请号：EP85902234.0

申请日：1985-04-08

Applicant: Hughes Aircraft Company

Inventor： HALMOS, Maurice, J. ,  HENDERSON, David, M.

IPC: H01S3

CPC classification number: H01S3/1398 ,  H01S3/107

Abstract: Un système de laser à pépiement comprend un cristal électro-optique de cavité interne qui est modulé à une fréquence relativement élevée, par exemple 250 kilohertz, pour effectuer un balayage de la fréquence du laser émetteur au-dessus et au-desous de sa fréquence centrale nominale. Un des miroirs associés au laser émetteur est réglable de manière à faire varier la longueur de la cavité du laser et ainsi décaler la fréquence du laser émetteur. Lorsque la fréquence du laser émetteur est décalée, l'amplitude de sortie du laser change quelque peu. Lorsque la fréquence centrale du laser se trouve à un point de gain maximum, l'amplitude des signaux de sortie pendant les excursions de fréquence positives et négatives du laser émetteur sont sensiblement symétriques. Toutefois, si un effet thermique ou autre provoque le décalage de la fréquence du laser du point de gain maximum, le signal de sortie pendant les excursions positives et négatives est asymétrique, le gain diminuant par exemple pendant une excursion montante de la fréquence et peut être augmentant ou ne diminuant pas autant pendant une excursion descendante de la fréquence. Une petite partie du signal de sortie provenant du laser émetteur est échantillonnée, et l'amplitude pendant les excursions positives et négatives de décalage de fréquence est comparée, en utilisant une onde rectangulaire dérivée du circuit d'attaque de modulation de pépiement. Quand les signaux détectés pour les excursions de fréquence positives et négatives sont sensiblement égaux, aucun changement dans la position du miroir n'est accompli; par contre, lorsque les excursions se traduisent par une différence d'amplitude des signaux détectés la position du miroir réglable par effet piézoélectrique est modifiée pour ramener la fréquence centrale nominale du laser à son point d'amplitude maximum sur la courbe de gain.