Can Light Waves Be Irregular? From what I understand, electromagnetic radiation produced by an antenna is of the frequency that corresponds to the motion of the electrons moving around in the antenna. And I assume that the electrons in most set ups are generally vibrating in an approximately sinusoidal motion. But sinusoidal is definitely not the only periodic shape we can get electrons to vibrate in. We can have square waves or saw-tooth waves.
My question is is there any detectable difference or any additional theoretical property individual photons have that are produced or carry some other non-sinusoidal wave shape, or are photons' energy states fully described by their frequency?
To be clear I'm interested in the resulting properties of individual quanta and not statistical group properties.
 A: Although you might drive your antenna (and the internal electrons) with a sawtooth wave, the resulting antenna emission is decomposed into "modes" of the antenna, which depend on the length, shape etc.  The Mode will correspond to photons (well, in antennas you usually think of Electromagnetic waves) which can radiate, and electromagnetic waves only self-propel themselves if the Electric & Magnetic fields are Sines or Cosines (since the relations between electric & magnetic fields are time derivatives; a sine creates a cosine and vice-versa).
So I think the "photons" will still be described as sinusoids.  However, the antenna will probably output many different frequencies of photons (EM-waves), so the sawtooth wave will look like it's been decomposed into however many sinusoidal EM-waves by the antenna.
Any photon that couldn't be described as a self-propagating sinusoidal wave would instead be "evanescent" - it will die out quickly, eg. a decaying exponential.  
Whether the "photon" is really a sawtooth shape, or is really a superposition of many sinusoids, is sort of due to how we define photons and electromagnetic waves - presumably you could describe the same situation without only sinusoidal electromagnetic "photons" (or photon-packets as it were), but that's how all the math I've ever seen does it.
